1. How to find multiple keywords at the same time
For example, I want to highlight all aa, bbbb, ccccc in the document

2. Examples
There is an enumeration

enum Test {
 TEST_A,
 TEST_BBBBB,
 TEST_CC,
 TEST_DDDDDDD,
 TEST_EEE
 };

How to quickly add the following comments

enum Test {
 TEST_A,         // 0
 TEST_BBBBB,     // 1
 TEST_CC,        // 2
 TEST_DDDDDDD,   // 3
 TEST_EEE        // 4
 };

For question 2, combining your answers with my own modifications, I used the following method:

1. set ve=allSo that the cursor can reach a place without characters
2. C-vEnter the column block visual mode and select the column to insert comments into
3. PressAAnd insert// 0, pressEscReturn to normal mode
4. VIn line visual mode, select all lines to which comments have been added.
5. executive commandlet i=0|'<,'>g/0$/s//\=i/|let i=i+1
6. set ve=Restore virtual editing options