The command mode of Vim changes to insert mode
one。 Enter the following shortcut in command mode
I insert characters before the current cursor
I insert characters at the beginning of the current line
An inserts a character after the current cursor
An inserts a character at the end of the current line
O start a new line under the current line
O start a new line above the current line
two。 Replacement mode
R replace cursor current character
R replaces the cursor and the following characters until you press ESC
