pls check if my unix answers are correct and provide corrections if necessary(commas separate the commands)

Move cursor to the last line of the file with one key: G

Use one key to move cursor to bottom line of screen: L

Move cursor to line 32 with three keys: <32>G

Turn on/off line numbers: :set nu , :set nonu

Forward/backward one page: ctrl-f , ctrl-b

Join the current line with next line: J

Replace the whole current line with abc with five keys:

Append text abc at the end of current line: A

You just deleted one line by accident. Undo this with one key: u

Delete next six lines including current line with three keys: 6dw

Delete from cursor to the rest of current line with one key: D

Save your changes without quitting vi: :w

Delete next five lines from current line and paste them back at the end of the file: 5dd, p

Delete next seven characters from cursor with two keys: 7x

Swap current char with the next one with just two keys: r

Temporarily leave vi as a background process and then come back to vi: ctrl-z

You are in vi with file science.txt, turn on search highlight and find all strings of child: :set hlsearch , / , ?

You are in vi with file science.txt, replace all thes with abc without prompt: :n,m s///g

Clear the highlights from last search: :set hlsearch!

Read a file a.cpp into vi below the current line: :r