21. The most important thing about cotton in history is ___part that it played in ____Industrial Revolution.
A. /,/ B. the,/ C. the , the D. a ,the
22. If Rose ____ her diamond in a safer place, it ____ stolen.
A. had put; might not have been B. had put; could be
C. had put; might be D. had not put; could not have been
