21. The bell rang and came in Mr. Brown, _____ a book in his hand. Then the class began.
A. for B. when C. with D. while
22. — _____ for the glass!
—It’s OK. I’m wearing shoes.
A. Look out B. Walk out C. Go out D. Set out
23. I don’t know why she suggested that we _____ the work before dark.
A. finishing B. finish C. would finish D. to finish
