I can’t use Ctrl to copy things when I use “MOVE” this instruction

How can I do?
I can’t use Ctrl to copy things when I use “MOVE” this instruction.

When you tap the CTRL key you should see the cursor change to have a + sign. While it has the + showing it will make a copy when you do the move.

Why I tap the CTRL key but can’t see the + sign?
This problem has bother me for a while.

Perhaps you’re using a Mac. If you are, it would be the Option key that you tap.

I use Windows,and I can use this function before still one day open the SketchUp.

But if it didn’t work what setting should I check
I even download again the Sketchup