He taught his father how to get to know ________ is going on in his university life on the Internet.
Professor Wang has written some short stories, but he is______ known for his plays.
This is the very information _______ we can learn what is selling best in the market. .
All _____ can be done has already been done.
The girl ______in red is a successful writer, who _______ Tom last month.
Mr. Smith doesn’t believe that his daughter can work out the problem that easily,_____?