How to select by keyboard?
After selecting , I click Menu's Edit, it shows 'Copy '.
How to type copy by keyboard?
Press Ctrl-Space to mark start of block.
Move cursor until end of block.
Press Alt-w to copy
Move to insert position
Press Ctrl-y to paste
I found another way just the same as windows' operations.
Emacs menu > Options > C-x/C-c/C-v Cut and Paste (CUA).
That option will let me use Shift+Arrow keys to select, Ctrl+C to copy, and ctrl+V to paste.
But it only work in emacs. It could not paste on gedit.
If I want to paste to gedit, I should use menu > edit > copy.
I didn't find any shortcut to menu > edit > copy.