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This post was last edited by baodingzhai on 2009-7-20 18:17. True or False question: 1. The NIM (Network Interface Module) provides a channel between LCN and UCN. ( ) Answer: Correct. 2. Digital communication is possible between the intelligent transmitter interface card and Honeywell intelligent transmitters, but it is one-way. ( ) Answer: Incorrect. 3. Smart transmitters can be calibrated using US or GUS. ( ) Answer: Correct. 4. The installation of the probe should generally be carried out when the unit is at rest. Answer: Correct 5. The transducer element of a condition monitoring system is the probe. Answer: Incorrect. 6. For the 3300 series condition monitors, when the hazard bypass switch is set to ON, the unit will not shut down in response to an alarm even if the hazard alarm setpoint is exceeded. Answer: Correct. 7. When installing an axial displacement probe, there is only one zero reference position. Answer: Incorrect. 8. The self-locking operating mode of the electro-hydraulic slide valve is superior to the self-protection operating mode. ( ) Answer: Incorrect. 9. The electro-hydraulic slide valve consists of a hydraulic control system and an electrical control system. ( ) Answer: Correct 10. The electro-hydraulic slide valve has the function of adjusting the range of piston displacement in the working cylinder. ( ) Answer: Correct 11. The electro-hydraulic slide valve has a function for resetting the initial position of the piston in the working cylinder. ( ) Answer: Correct 12. The electro-hydraulic slide valve has the function of adjusting the working direction in both forward and reverse directions. ( ) Answer: Correct 13. The electro-hydraulic slide valve has a tracking bandwidth adjustment function, with the adjustment range being 0.5–5% of the full scale corresponding to changes in the input signal. ( ) Answer: Correct. 14. The smaller the operating power of a relay, the higher its sensitivity. ( ) Answer: Correct. 15. The methods to release a relay are direct power cutoff, parallel connection of resistors, and parallel connection of the power supply. ( ) Answer: Correct. 16. After powering on the signal interlocking system, if there are no abnormal conditions such as overheating in various instruments and relays within half an hour, then a no-load test can be carried out. ( ) Answer: Correct 17. Sometimes, it is permissible from a technical standpoint for parameters to exceed their limits for short periods of time; in order to prevent the alarm system from triggering alarms too frequently, a delayed alarm system can be used. ( ) Answer: Correct 18. In signal alarm interlocking systems, in order to reduce the likelihood of incorrect operations in the interlocking circuits and improve the reliability of these interlocking actions, a three-to-two voting circuit can be used. Answer: Correct. 19. A float is used to measure liquid level; when the float falls off, the instrument outputs a maximum value. ( ) Answer: Correct. 20. When calibrating a thermistor temperature transmitter, the signal sent should have the room temperature subtracted from it. ( ) Answer: Incorrect. 21. When using a float to measure liquid level, the instrument outputs the minimum value once the float falls off. ( ) Answer: Incorrect. 22. To measure the magnitude of a certain voltage, the measurement circuit must draw current from the voltage in question. ( ) Answer: Incorrect. 23. When the regulator’s measured value is greater than the set value, the output signal decreases, which is a positive-action behavior. ( ) Answer: Incorrect. 24. The automation of oil refinery operations refers to the automatic functioning of the equipment with no need for human intervention at all. ( ) Answer: Incorrect. 25. In a cascade control system, the control law used for the secondary controller is generally proportional control, while the primary controller employs proportional-integral control. ( ) Answer: Correct. 26. When using a thermocouple to measure temperature, if compensating wires are used for the connection wires, it is not necessary to consider compensation for the cold end of the thermocouple. ( ) Answer: Incorrect. 27. The level indication of a float-type level gauge is related to the density of the medium being measured. ( ) Answer: Incorrect. 28. In proportional control, the smaller the proportionality constant δ, the weaker the control effect, and oscillations will not occur. ( ) Answer: Incorrect. 29. If the accuracy of the watch to be calibrated is grade 1.5, then the accuracy of the standard watch should also be chosen as grade 1.5. ( ) Answer: Incorrect. 30. The logical OR relationship means that something will occur only when all the conditions necessary to determine it are met. ( ) Answer: Incorrect. 31. In flow measurement, when negative pressure is completely blocked while positive pressure flows freely, the trend in the instrument’s readings is opposite to the trend in flow rate. Answer: Incorrect. 32. When the regulation process is unstable, the integration time can be increased or the proportional gain can be raised to stabilize it. Answer: Correct. 33. For a transformer with n=2 and an input voltage of 15V, the output voltage is 7.5V. Answer: Correct. 34. When using an orifice plate to measure flow rate, the orifice plate should be installed in front of the control valve. Answer: Correct. 35. Regarding the range of a differential pressure transmitter, it can be adjusted arbitrarily as long as it is less than the standard range value of the instrument. Answer: Incorrect. 36. The use of differential action in control systems can eliminate pure lag. Answer: Incorrect. 37. The caisson rises and falls along with the liquid level, just like the float. Answer: Incorrect. 38. When performing a fault check on a primary gauge, the regulator must first be set to the manual operation mode. Answer: Correct. 39. When the counterweight of a float level gauge is at its highest position, the actual liquid level is at its highest as well. Answer: Incorrect 40. When checking back-blow type measuring instruments, instead of closing the isolation valve, the dirt is discharged from the instrument through the vent. Answer: Incorrect 41. A thermocouple must be composed of two different materials. Answer: Correct 42. The grounding system of a Zener-type safety barrier should not be connected to other grounding systems. Answer: Correct. 43. If the reading of a thermistor thermometer is low, it is possible that the thermistor is short-circuited. Answer: Correct 44. The gauge pressure measured using a U-tube manometer is related to the cross-sectional area of the glass tube. Answer: Incorrect. 45. Red copper is pure copper, and it possesses good electrical and thermal conductivity, as well as resistance to atmospheric corrosion. Answer: Correct. 46. When a gray clog occurs in the zirconia probe, it will cause slow responses in the measurement results. Answer: Correct. 47. 1151 differential pressure transmitters with different measurement ranges differ due to the material of their measuring diaphragms. Answer: Incorrect. 48. When using a multimeter, the red test lead should be connected to the positive terminal, and the black test lead should be connected to the negative terminal. Answer: Correct 49. Automatic adjustment is also known as automatic control. ( ) Answer: Incorrect. 50. Automatic regulation is a form of quantitative control, and it is not necessarily a closed-loop system. Answer: Correct 51. When using a differential pressure transmitter to measure flow rate, the differential pressure is proportional to the square of the flow rate ( ). Answer: Incorrect 52. The output signal of a temperature transmitter is in millivolt form ( ). Answer: Incorrect 53. Since pressure is now measured using the International System of Units, 1 KPa = 1000 mmH2O ( ). Answer: Incorrect 54. When using a double-flange differential pressure transmitter to measure liquid level, the range of the transmitter should equal the difference between positive and negative pressures multiplied by the specific gravity of the medium ( ). Answer: Correct 55. An improper insertion depth of the thermocouple can result in lower readings from the instrument ( ). Answer: Correct 56. Throttling devices must be installed on straight pipelines ( ). Answer: Correct 57. When wiring a Cu50 thermal resistor, it is important not to reverse the positive and negative connections ( ). Answer: Incorrect 58. When reading the signal from a Pt100 sensor, the ambient temperature must be taken into account ( ). Answer: Incorrect 59. In float-type level measurement devices, the indicated value is related to the density of the medium ( ). Answer: Incorrect 60. When the measured value by the regulator is greater than the set value, the output signal decreases, which is characteristic of a positive-action system. ( ) Answer: Incorrect. 61. In a cascade control system, the control law used for the secondary controller is generally proportional control, while the primary controller uses proportional-integral control. ( ) Answer: Correct. 62. In proportional control, the smaller the proportionality constant δ, the weaker the control effect, and oscillations will not occur. ( ) Answer: Incorrect. 63. The logical AND relationship means that something will occur only when all the conditions necessary for it to happen are met. Answer: Correct. 64. In flow measurement, when negative pressure is completely blocked while positive pressure is unobstructed, the trend of the instrument’s indication is opposite to that of the flow rate change. Answer: Incorrect. 65. When the regulation process is unstable, the integration time can be increased or the proportional gain can be raised to stabilize it. Answer: Correct. 66. The use of differential action in control systems can eliminate pure lag. Answer: Incorrect. 67. When performing a fault check on a primary gauge, the regulator must first be set to the manual operation mode. Answer: Correct. 68. The grounding system of a Zener-type safety barrier should not be connected to other grounding systems. Answer: Correct. 69. When a gray fouling occurs in the zirconia probe, it will cause slow responses in the measurement results. Answer: Correct. 70. For an output safety barrier, when it is damaged, the output wires can be temporarily bridged. ( ) Answer: Correct. 71. When the float of a float level gauge comes loose, the output indication becomes zero. ( ) Answer: Incorrect. 72. When using a thermal resistor for temperature measurement, if the thermal resistor is open-circuited, the temperature reading will be at its lowest value. ( ) Answer: Incorrect. 73. To start the float level gauge, the negative pressure valve should be opened first. ( ) Answer: Correct. When adjusting the range of a 74.FC differential pressure transmitter, coarse adjustment and fine adjustment can be carried out simultaneously. ( ) Answer: Correct 75. Both target flowmeters and rotameters are based on the principle of fluid resistance conversion. Answer: Correct. 76. Like the throttling differential pressure flow meter, the target flow meter is also based on the principle of throttling. Answer: Wrong. 77. The greater the flow rate, the greater the force exerted on the target. Answer: Correct. 78. During verification, open the drain valve at the bottom of the float chamber, and then connect a plastic tube to fill it with water for verification. Some people say that this plastic tube must be vertical just like the buoy chamber in order to ensure accurate calibration. Answer: Incorrect. 79. The level indication of a float-type level gauge is related to the density of the medium being measured. Answer: Incorrect. 80. The more decimal places there are in a measurement value, the more precise the measurement is. Answer: Wrong. 81. When the counterweight is in the middle, the actual liquid level is also in the middle. Answer: Correct. 82. The output air pressure reaches its maximum value after the float ball comes off. Answer: Correct. 83. Since the compensation wire serves as an extension of the thermocouple, the thermocouple potential depends only on the temperatures at the hot and cold ends, and not on the temperature at the point where the compensation wire connects to the thermocouple. Answer: Incorrect. 84. The oxygen content in air is 20.6%. Answer: Correct. 85. When the control process is unstable, increasing the integration time or the gain of the controller can help stabilize it. Answer: Correct. 86. The residual error in a proportional control process is proportional to the gain of the controller. Answer: Correct. 87. The temperature measurement range of copper thermistors is wider than that of platinum thermistors. Answer: Incorrect. 88. When soldering transistor circuits with a soldering iron, an internal-heating type soldering iron with a power rating of 25–45W is usually used. ( ) Answer: Correct. 89. If the soldering iron tip oxidizes due to excessive heat, it can be shaped using a file. ( ) Answer: Incorrect. 90. When using a multimeter to measure resistance, the resistor being tested can be powered. ( ) Answer: Incorrect. 91. A multimeter is generally used to measure direct current, voltage, as well as alternating current and voltage. ( ) Answer: Correct. 92. When using a multimeter to measure the resistance of a diode, the resulting resistance value depends on the resistance range selected. （ ） Answer: Correct. 93. When using a megohmmeter, the speed at which the handle is turned should not be too fast or too slow; the recommended speed is 120 revolutions per minute. ( ) Answer: Correct. 94. A megohmmeter has two terminals. ( ) Answer: Incorrect. 95. The value indicated by an AC ammeter is the effective value. ( ) Answer: Correct. 96. An ammeter connected directly to a circuit must be connected in parallel with the circuit being measured. （ ） Answer: Incorrect. 97. In order not to affect the operation of the circuit, the internal resistance of a voltmeter should be very low; the lower the internal resistance, the greater the measurement range. () Answer: Incorrect. 98. DC voltmeters typically use a magnetoelectric measuring mechanism. ( ) Answer: Correct. 99. A common DC potentiometer serves both as a measuring instrument and as a signal output instrument. （ ） Answer: Correct. 100. The measurement range of a current potentiometer is generally not less than 2V. ( ) Answer: Incorrect. 101. The viscosity of hydraulic oil decreases as the temperature rises. ( ) Answer: Correct. 102. The oil level in the equipment’s fuel tank should be kept at above 2/3 of the tank’s capacity. ( ) Answer: Correct. 103. The wind-operated valve opens when there is no wind. ( ) Answer: Incorrect. 104. If the signal from the zirconia probe is too high, the measurement result will be too low. ( ) Answer: Correct. 105. Based on the type of energy used, control valves can be divided into pneumatic control valves, electric control valves, and hydraulic control valves. ( ) Answer: Correct. 106. To measure the current in a circuit, the ammeter must be connected in parallel with that circuit. ( ) Answer: Incorrect. 107. A simple control system consists of three main components: the controlled process, the transmitter, and the controller. （ ） Answer: Incorrect. 108. If the signal from the zirconia probe is too high, the measurement result will be too low. ( ) Answer: Correct. 109. When pressure transducers are used to measure flow rate, if there is a leak in the valve or pipeline on the positive pressure side, the instrument will show a lower reading. ( ) Answer: Correct. 110. When installing a target flowmeter, it is necessary to ensure that the center of the target is concentric with the pipeline axis, and that there are sufficient straight sections of pipe in front of and behind the instrument as required. ( ) Answer: Correct. 111. Target flowmeters are suitable for measuring the flow rate of fluids with low Reynolds numbers; therefore, there is no such thing as a critical Reynolds number. ( ) Answer: Incorrect. 112. Poor contact between the thermocouple terminals and the thermal electrodes will result in unstable thermoelectric potential output. ( ) Answer: Correct. 113. In a simple control system, if the object and the transmitter have a positive effect, and the control valve is of the air-operated type, then the controller must be a positive-action controller. ( ) Answer: Incorrect. 114. From a correct instrument control flow diagram, it is possible to obtain information about the instruments such as the type of transmitter, the operation mode of the regulator, and the type of actuator. ( ) Answer: Correct. 115. Using compensation wires, also known as thermocouple connection wires, is intended to compensate for the potential difference that arises at the cold end of a thermocouple due to changes in ambient temperature. ( ) Answer: Correct. 116. When using a differential pressure transmitter to measure liquid level, to check its zero point, close the positive and negative pressure valves, open the balance valve, and adjust the shift spring so that the output is 100%. ( ) Answer: Incorrect. 117. When using the differential pressure method to measure the liquid level in a container, the level height depends on the location of the pressure measurement points. ( ) Answer: Incorrect. 118. If the temperature inside the device is around 200°C, a thermal resistor is intended to be used for measurement; since copper resistors are inexpensive, they can be chosen for this purpose. ( ) Answer: Incorrect. 119. In a cascade control system, the secondary controller performs fine tuning, while the primary controller carries out coarse tuning. ( ) Answer: Incorrect. 120. A cascade control system is composed of simple controllers connected in series. ( ) Answer: Incorrect. 121. The gap voltage value at the zero point of the Bentley displacement monitor is 1 V. ( ) Answer: Incorrect. 122. Next to the zero-setting screw of a primary instrument, the fine-tuning position for setting the instrument’s zero is usually marked as ZERO. ( ) Answer: Correct. 123. The duration of secondary safety training shall be no less than 24 hours. ( ) Answer: Correct. 124. Safety procedures can be skipped when work requires it, and work can be carried out directly. ( ) Answer: Incorrect. 125. The safety production responsibility system is the most fundamental safety system in a enterprise, and it constitutes the core of safety regulations and rules. ( ) Answer: Correct. 126. When it is detected that a worker has consumed alcohol and is in a lethargic state, working at heights is prohibited. ( ) Answer: Correct. 127. Welding work in sewage treatment plants, areas where flammable and explosive materials are present, as well as in recirculation water systems, cooling towers, and oil separation tanks, oil ditches, and pipes within industrial wastewater systems is classified as level 1 welding work. ( ) Answer: Correct. 128. If there are oil stains on the work clothes, they can be cleaned with gasoline. ( ) Answer: Incorrect. 129. The standard gases used for calibrating analytical instruments can be prepared by oneself. ( ) Answer: Incorrect. 130. The working principle of the H2S gas alarm sensor is catalytic combustion. ( ) Answer: Incorrect. 131. The stronger the acidity of a solution, the lower the value displayed by the pH meter. ( ) Answer: Correct. 132. The oil collection hopper of the large crane pipe cannot be raised if it is not at the upper limit position. ( ) Answer: Correct. 133. The reason why the large hose crawler vehicle cannot move forward is usually that the hose is not at its upper limit position. ( ) Answer: Correct. 134. Smart transmitters can be calibrated using GUS. ( ) Answer: Correct. 135. A PID control system refers to a control system that utilizes proportional, integral, and derivative actions. ( ) Answer: Correct. 136. In the HONEYWELL company’s TPS system, calling up flowcharts can only be done using the SCHEM key. ( ) Answer: Incorrect. 137. In the point parameters, PVEUHI and PVEULO represent the upper and lower limits of the engineering units for the measurement range, respectively. ( ) Answer: Correct. 138. The LCN communication cables in HONEYWELL’s TPS system are configured in a redundant manner (LCNA/B); automatic switching is possible, but manual switching is not. ( ) Answer: Incorrect. 139. The invocation of the flowchart in HONEYWELL’s TPS system can be done using custom keys. ( ) Answer: Correct. 140. Intelligent transmitters allow for parameter adjustment online. ( ) Answer: Correct. 141. The EJA transmitter allows for zero adjustment both online and on the instrument itself. ( ) Answer: Correct. 142. The two wires of the SFC communicator have positive and negative poles, and they must not be swapped arbitrarily. ( ) Answer: Correct. 143. The D/E protocol is used for transmitting digital signals superimposed on analog signals simultaneously. ( ) Answer: Incorrect. 144. The activation and deactivation of the interlocking system can only be carried out after an approval form has been issued. ( ) Answer: Correct. 145. The letter combination “LSLL” for instrument tag numbers denotes low-low level interlock. ( ) Answer: Correct. 146. A standard resistance box is a device used to measure units of resistance. ( ) Answer: Correct. 147. The allowable error of the standard instrument used to calibrate another instrument shall not be more than 1/3 of the allowable error of the instrument being calibrated. ( ) Answer: Correct. 148. In the block diagram of a control system, each block represents a device or component with a specific function. ( ) Answer: Correct. 149. Current signals of 4–20 mA DC from the field, thermocouple signals, and thermal resistor signals are all analog signals. ( ) Answer: Correct. 150. The most suitable device for detecting liquid level alarms is a capacitive level switch. ( ) Answer: Correct. 151. When using a thermocouple to measure the temperature in a furnace, if it comes into direct contact with the flame, the temperature reading will be too high. ( ) Answer: Correct. 152. The control law for a uniform regulation system is generally chosen to be PI or P. ( ) Answer: Correct. 153. When a compressor experiences surge, its operating point fluctuates back and forth between the surge region and the non-surge region. ( ) Answer: Correct. 154. The three basic conditions for a substance to burn are a combustible material, an oxidizing agent, and a heat source. ( ) Answer: Correct. 155. The three-level safety education system is the basic framework for safety education in enterprises, comprising company-level, workshop-level, and team-level education. ( ) Answer: Correct. 156. High-altitude work is divided into two categories: ordinary and special. Work carried out at heights between 2 meters and 30 meters above the working surface is considered ordinary high-altitude work. ( ) Answer: Correct. 157. Hydrogen sulfide is a colorless gas that has an odor similar to that of rotten eggs at low concentrations; at high concentrations, it can impair the sense of smell, making it difficult to determine its harmful concentration based on smell alone. ( ) Answer: Correct. 158. “Three violations” refer to giving illegal instructions, carrying out illegal operations, and violating labor discipline. ( ) Answer: Correct. 159. The “3E” strategies for accident prevention are technical measures, educational measures, and management measures. ( ) Answer: Correct. 160. The working principle of the probe in a combustible gas alarm is catalytic combustion. ( ) Answer: Correct. 161. When the heating indicator light of the JZY-11 zirconia detector goes out, the heating coil is open-circuited. ( ) Answer: Correct. 162. The ideal ratio for a H2S/SO2 ratio analyzer is 2:1. ( ) Answer: Correct. 163. When the regulator is in manual mode, the operator can directly control the output. ( ) Answer: Correct. 164. When the operator sets the regulator to automatic mode, the operator can directly adjust the set value. ( ) Answer: Correct. 165. The secondary loop regulator in cascade mode should normally be in cascade control mode. ( ) Answer: Correct. 166. In HONEYWELL’s TPS system, if zener safety barriers are used, the maximum ground resistance of the main reference ground is 1Ω ； Otherwise, the maximum earth resistance of the main reference ground is 5Ω. ( ) Answer: Correct. 167. The key lock OPR on the GUS operation station stands for operator. ( ) Answer: Correct. 168. The key lock SUP on the GUS operation station represents the team leader. ( ) Answer: Correct. 169. The key lock ENG on the GUS operation station stands for engineer. ( ) Answer: Correct. 170. In HONEYWELL’s TPS system, a maximum of 10 consoles can be defined on the LCN network. ( ) Answer: Correct. 171. On the LCN network of HONEYWELL’s TPS system, one console can have up to 10 operation stations. ( ) Answer: Correct. 172. The common control modes for control points are manual, automatic, and cascade. ( ) Answer: Correct. 173. In the DCS point parameters, PVHITP represents the high-limit alarm value for the PV value. ( ) Answer: Correct. 174. In the DCS point parameters, PVLOTP represents the low-limit alarm value for the PV value. ( ) Answer: Correct. 175. The LLMUX low-level multi-channel analog input card can receive and process 32-point thermistor or thermocouple input signals. ( ) Answer: Correct. 176. The polypropylene powder is transported from the silo to the packaging machine using a screw conveyor. ( ) Answer: Correct. 177. It is the inductive proximity switch that is used to detect the current position of the large hose. ( ) Answer: Correct. 178. The inductive proximity switch is used to detect the current position of the oil receiving hopper in large hose systems. ( ) Answer: Correct. 179. The fiber-optic level sensor is used to detect the liquid level in tank cars. ( ) Answer: Correct. 180. When the cam of the polypropylene discharge valve’s feedback device becomes loose, it affects the ability of other reactors to continue transporting powder. ( ) Answer: Correct. 181. The microwave transmission frequency of radar level gauges is generally between 1 and 5 GHz. ( ) Answer: Correct. The 182, 1151 differential pressure transmitters use a variable capacitor as the sensing element; when the differential pressure increases, the measuring diaphragm moves, resulting in an increase in capacitance on the low-pressure side and a decrease in capacitance on the high-pressure side. ( ) Answer: Correct. 183. In the model of a flanged differential pressure transmitter, the presence of the letter “A” indicates that positive migration is possible ； A “B” indicates that negative migration is possible. ( ) Answer: Correct. 184. The condition for a thermocouple to generate a thermoelectrical potential is that the materials of the two thermal electrodes are different, and the temperatures at the two junctions are also different. ( ) Answer: Correct. 185. After the compensation wires are installed, an insulation test should be conducted using a 500V megohmmeter to check the insulation between the wires and between the wires and the ground; the insulation resistance should be higher than 5MΩ. ( ) Answer: Correct. 186. The measurement of liquid level using a float-type level gauge is based on Archimedes’ principle. ( ) Answer: Correct. 187. When the liquid level is at its highest, the float of a level gauge is completely submerged in the liquid; the buoyant force acting on the float is at its maximum, the torque generated by the torsion tube is at its minimum, and the output signal is at its maximum. ( ) Answer: Correct. 188. To open the vent valve of the buoyancy chamber, it is necessary to first close the shut-off valves upstream and downstream. ( ) Answer: Correct. 189. When using a float-type level gauge to measure liquid levels, the maximum measurement range is determined by the length of the float. ( ) Answer: Correct. 190. When a thermocouple or compensation wire is short-circuited, the reading on the display instrument is approximately equal to the temperature at the point of short-circuiting. *It is customary to say that the instrument indicates room temperature in such cases. ( ) Answer: Correct. 191. The magnitude of the thermoelectric potential of a thermocouple depends on the materials that make up the thermocouple as well as the temperatures at its two ends; it is not related to the thickness or length of the thermocouple wires. ( ) Answer: Correct. 192. Deviation refers to the difference between a given value and a measured value. ( ) Answer: Correct. 193. When using a throttling device to measure flow rate, the throttling device should be installed behind the control valve. ( ) Answer: Incorrect. 194. When using a standard throttling device for flow measurement, the fluid must fill the pipeline and flow through it continuously. ( ) Answer: Correct. 195. The rotameter must be installed vertically in the pipeline, with the flow direction of the medium being from top to bottom. ( ) Answer: Incorrect. 196. In the case of a fire caused by electrical issues, and there are live wires and equipment at the scene of the fire, firefighters must first try to cut off the power supply. ( ) Answer: Correct. 197. When using a dry powder fire extinguisher to put out a fire, it is necessary to aim at the upper part of the flame. ( ) Answer: Wrong. 198. If your clothes catch fire, run quickly and find someone to help put out the fire. ( ) Answer: Incorrect. 199. When using a filter-type gas mask, the oxygen content in the air should be no less than 16%, and the concentration of toxic gases should not exceed 2%. ( ) Answer: Correct. 200. The safety belt must be fastened to a secure fixture above the work area; it should be worn in such a way that it is low on the body but high above the ground. ( ) Answer: Incorrect