Brother, in my experience, I suggest you look at the CAD help system if you don't understand it, or ask Baidu, where there are experts like a cloud, and general problems can be solved. The easiest way is to press F 1 every time you start CAD. When you can't, look up the command you want in the index or search, and the meaning comes out. In addition, if you understand the meaning of 26 English letters in CAD, you will learn CAD, and remember that shortcut keys get twice the result with half the effort! It's that simple. Attached is my usual shortcut command, which can be understood at a glance:

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There are many Z CO CP OP OS MO AR REV REG BO, which I often use. You can understand the specific usage as soon as you search in the help system! ! ! Wish you success! ! !