There are several multiple-choice questions from the 2018 issue of \"Safety Production Technology\"; please share the answers. Are there any discussions on this?

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II. Multiple-choice questions (15 questions in total, 2 points for each question. Among the options for each question, 2 or more are in line with the requirements, and there is at least 1 incorrect option. Wrong choice; no points for this question ； Choose fewer options; each selected option is worth 0.5 points. )61. During welding and cutting, the temperature of the flying sparks and molten metal particles can reach 1500°C–2000°C, and they can travel up to 20 meters in the air. Which of the following precautions for welding and cutting operations are correct? （ ） A. When working with fire in flammable and explosive areas, the system and the surrounding environment must be thoroughly cleaned or purified. B. If the lower explosive limit of a gas is greater than 4%, its concentration in the environment should be less than 1%. C. Metal components connected to flammable and explosive production equipment can be used as welding ground wires. D. The area where welding is carried out must be equipped with appropriate fire-fighting equipment. E. When performing oxy-acetylene welding, the acetylene generator should be placed in a safe location. 62. The moving parts of rotating machinery are the parts most prone to entanglement hazards; therefore, different protective measures must be taken for different types of machinery to reduce the risk of such entanglements. Which of the following requirements for measures to prevent entanglement in the mechanically rotating parts are correct? A. Smooth shafts without protrusions pose a risk of catching and entangling clothing while rotating; therefore, guards should be installed on their exposed parts. B. For rotating shafts with protrusions, these protrusions can catch clothing and human bodies, so such shafts should be fitted with fully enclosed protective covers. C. In the case of counter-rotating rollers, even if the distance between adjacent rollers is large, there is still a risk of limbs being trapped; hence, clamping-type guards should be used for protection. D. For roller conveyors driven by alternating roller shafts, protective guards should be installed upstream of the moving roller shafts. E. When feeding materials using traction rollers, to prevent entanglement, protection measures such as installing clamping strips at the openings or reducing the size of those openings should be employed. 63. Insulating materials have various performance indicators, among which electrical properties are one of the important ones. Among the following performance indicators, those that belong to electrical performance indicators are ( ). A. Insulation resistance B. Withstand voltage strength C. Arc resistance D. Dielectric loss E. Leakage current 64. The grinding wheel assembly consists of a grinding wheel, spindle, chuck, shims, and fastening nuts, as shown in the figure. The focus of safety protection for grinding wheel devices lies on the grinding wheel itself; the safety of the grinding wheel is directly related to the safety measures for components such as the spindle and chuck. Which of the following safety requirements for the grinding wheel spindle and chuck are correct? A. The non-contact area between the chuck and the side of the grinding wheel should have a gap of less than 1.5 mm. B. The diameter of a chuck designed for general use must be at least 1/3 of the grinding wheel’s diameter. C. The threads at the end of the spindle must be long enough to allow the nut to be screwed in fully to achieve proper compression. D. The threaded portion of the spindle extends into the compression surface of the fixing nut, but it must not exceed 1/2 of the length of the inner hole corresponding to the grinding wheel’s minimum thickness. E. The rotation direction of the spindle threads must be the same as that of the grinding wheel during operation. 65. The basic function of a safety device is to create a protective barrier between people and potential hazards; therefore, such devices must meet the requirements appropriate to their protective functions. Which of the following requirements for safety protection devices are correct? （ ） A. Safety protection devices should be able to perform their functions properly throughout the machine’s service life and ensure reliability. B. The components of safety protection devices must possess sufficient strength and stiffness. C. Safety protection devices should be easy to disassemble. D. The use of safety protection devices should not increase the difficulty or intensity of operation. E. Safety protection devices should not introduce any additional hazards. 66. By taking into account the various characteristics of both humans and machines, it is possible to allocate tasks effectively between them, thereby achieving high efficiency in the system. Regarding the statement on assigning functions based on the characteristics of humans and machines, which of the following are correct? A. Machines have superior persistence and reliability compared to humans, so tasks that require long-term, reliable operation can be entrusted to them. B. Humans have better adaptability to their environment than machines, which makes it difficult to assign work in harsh or dangerous environments to machines. C. Machines are more accurate in detecting physical and chemical factors than humans, but they are less capable of handling flexible objects or problems involving multiple factors. D. Humans can use more different channels to receive information and process it more flexibly, while machines usually handle problems according to pre-set programs. E. Traditional machines lack the learning and reasoning abilities of humans; therefore, human intervention is still needed for making decisions regarding complex problems. 67. The fire hazard associated with asynchronous motors stems from internal or external factors such as manufacturing defects, operational failures, and poor management. Which of the following factors can cause fires in asynchronous motors? A. Fluctuations in supply voltage and excessively low frequency B. The current protection setting for the motor is too low C. Overloading or stall occurring during motor operation D. Damage to the motor’s insulation, resulting in inter-phase short circuits E. Broken wires in the windings or poor connections 68. Good insulation is a necessary condition for the proper operation of electrical equipment and circuits. When selecting insulating materials, their suitability for the surrounding environment must be taken into account. In which of the following situations could insulation damage occur? A. Quartz insulation is used in normal temperature environments. B. Mineral oil insulation contains too many impurities. C. Ceramic insulation is used in environments exposed to wind and sunlight over long periods. D. Polyester paint insulation is used in environments with high voltages. E. Laminated cloth insulation is used in environments subject to mold erosion. 69. During the design of fireworks and firecracker factories, a certain safety distance should be maintained between hazardous buildings and sites and surrounding buildings; this distance is determined by taking the maximum value based on the hazard level of the buildings and the amount of explosives calculated. Which of the following requirements regarding the safety distance are correct? A. The distance between the enclosure wall and hazardous buildings or structures should be 12 m, and it must not be less than 5 m. B. A fire barrier should be established within 5 m of the outer walls of hazardous buildings or structures. C. The minimum allowable distance between hazardous buildings in the hazardous materials production area and the company’s main warehouse area should be determined based on the hazard level of the buildings and the amount of explosives being stored, with the higher value being taken. D. The minimum allowable distance between the edge of the explosive destruction site in fireworks manufacturing enterprises and the outer walls of buildings outside the site should be no less than 65 m; the amount of explosives destroyed at one time should not exceed 20 kg. E. The amount of explosives stored in the blast-resistant compartments within hazardous buildings must be included in the total amount of explosives considered for those buildings. 70. The annual inspection of pressure pipelines refers to the inspections carried out by the operating unit while the pipelines are in use. According to the “Rules for Periodic Inspection of Pressure Pipelines – Industrial Pipelines” (TSG D7005), the contents of an annual inspection of pressure pipelines include ( ). A. Determine the wall thickness of elbows that show signs of severe corrosion. B. Measure the anti-static grounding resistance of pipes used to transport flammable and explosive substances. C. Check the calibration period of safety valves. D. Conduct hardness testing on pipes where hardness requirements apply to the welds. E. Perform non-destructive testing on the outer surface of pipe welds. 71. Unlike 3D printing, metal casting is a traditional metal heat-processing technique for shaping metals; it involves processes such as sand preparation, molding, metal melting, casting, and post-casting treatment. Which of the following statements about safety and health measures in casting processes are correct? ( ) A. The rotating drum of the ball mill used in casting processes should be placed within a fully enclosed cover. B. The casting workshop should be located on the upwind side of those production buildings in the factory area that do not emit harmful substances. C. Dry, high-efficiency dust collectors should be used for the smoke purification systems of the melting furnaces used in casting. D. The air tanks and piping systems used for compressed air in casting processes should be equipped with limit, interlock, and safety devices. For jaw crushers used in casting processes, when feeding is done directly from above and the height difference is less than 1 meter, it is sufficient to use only an enclosed cover without the need for exhaust ventilation. 72. Each cab of a construction elevator should be equipped with a fall arrest device, which can stop the cab in case of overspeed or failure of the suspension mechanism, thereby preventing falls. Which of the following requirements for fall arrest devices are correct? （ ） A. When the weight of the elevator’s counterweight is less than that of the cab, a two-way fall arrest device should be used. B. When the cab is equipped with two safety devices, both should be of the progressive type. C. Wire rope-type construction elevators can use instantaneous safety devices. D. Gear and rack-type construction elevators should use constant-speed safety devices. E. Safety devices that act on two guide rods must function simultaneously during operation. 73. In the protective zero-grounding system, different requirements exist regarding the duration of faults for distribution circuits and those that supply handheld electric tools or mobile electrical equipment. Which of the following requirements regarding the duration of line failures are correct? （ ） A. For distribution circuits, the fault duration should not exceed 5.0 s. B. For circuits that supply fixed electrical equipment, the fault duration should not exceed 8.0 s. C. The fault duration for 220V circuits used with handheld power tools should not exceed 0.4 s. D. The fault duration for 380V circuits used with portable power tools should not exceed 0.2 s. E. The fault duration for 220V circuits used with portable power tools should not exceed 1.0 s