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This introductory tutorial on CAD drawing focuses on how to select identical or similar graphics and blocks in the HaoChen CAD software. When using the HaoChen CAD software for drawing, it is sometimes necessary to select identical or similar objects in order to perform the same operations, or to select all blocks with the same name in order to count their number or delete them all at once. The HaoChen CAD software offers various methods for finding identical or similar graphics and blocks. The choice of method depends on the common attributes of these graphics. Some methods are simple, but may not allow you to find the desired graphic; other methods enable the setting of various filtering criteria, making them relatively more complex to use. SELECT SIMILIAR: After selecting an object, the right-click menu provides options for similar objects and all unselected objects. It is quite convenient to select similar objects in order to pick objects of the same type or blocks with the same name. For example, if I want to select all the circles in the image, I first select one circle and then choose “Select Similar Objects” from the right-click menu; this will select all the circles on the same layer, as shown in the figure below. This function can also be used when it is necessary to count the number of certain types of blocks or to delete all instances of a particular block; it allows all blocks with the same name on the same layer to be selected, as shown in the figure below. However, this method allows selection only of objects of the same type on the same layer; objects of the same type on other layers or blocks with the same name cannot be selected. Since no conditions can be set, the results of the selection may not always be as we desire. Quick Selection (QSELECT): Quick selection allows all elements in a diagram that meet a certain condition to be selected by setting a filter criterion. The command for quick selection is Qselect (QSE); you can also invoke this command by clicking the quick selection button in the upper right corner of the property panel. The quick selection button can be found in the “Utilities” panel on the “Default” tab of the command panel in higher versions of HaoChen CAD. After opening the dialog box, you can set the application scope, object type, the properties and parameter values used for filtering, as well as the application method, as shown in the figure below. If an object has already been selected in the diagram, the application range above will change to “Currently Selected”. After setting the filter criteria, it is possible to filter the objects within the currently selected set based on those criteria, in order to select the objects that meet the conditions or exclude those objects from the selected set. If the Quick Selection filter is opened with no objects selected, the \"Apply to\" option will be the entire graphic; in other words, the filter criteria set below will be used to select elements within the entire graphic that meet those criteria, allowing such elements to be selected or excluded from the selection set. After opening this dialog box, you can also click the selection button in the upper right corner to select an object first before applying filtering. Quick selection can also be used multiple times depending on the situation; for example, we can first filter the blocks by layer, and then filter them again by block name, achieving a similar effect to selecting objects as described above. After that, further filtering can be done based on scale. The operation of quick selection is not complicated; it can be easily mastered after using it a few times, so no further detailed explanation is needed here. Object selection filter (FILTER): The object selection filter was originally a feature in the Haochen CAD extension tools, but it has now become a basic feature; the command is FILTER (FI). The object selection filter is somewhat similar to quick selection, but the difference is that the object selection filter allows multiple conditions to be set at once; these conditions can be combined using mathematical operations. It is also possible to click the “Add Selected Objects” button to select objects from the image in order to create conditions, and then delete any unnecessary conditions ； After setting the filter, it can be saved so that it can be used again when selecting a command filter, as shown in the figure below. The settings for selecting filters are more extensive and flexible; many people prefer using this command. For example, in the filtering criteria shown in the screenshot above, there is the condition “Layer=0”, and in this case the result of selecting a block is the same as when selecting similar objects. If the layer condition is removed, the selection result is similar to that of quick selection. There are other tools as well, but these functions sometimes fail to address some of the issues we encounter; for example, selecting blocks based on attribute values or other criteria. Therefore, there are many similar plugins available online. For instance, the HaoChen CAD extension tools developed in China include a series of selection tools that allow users to select graphics with identical attributes by picking an example graphic in the diagram – such as selecting blocks with the same name, objects on the same layer, or those with the same color. Since no need to set up filtering conditions, these tools are more convenient to use. For beginners in CAD drawing, it is common to find that many people want to learn more functions and find faster ways to draw. The tutorials we provide on the selection of CAD graphic blocks are quite useful, and they can serve as a reference for everyone.