16. If the work __ by the end of this month is delayed, the construction company will be heavily fined.
A. is completed B. to be completed
C. will have been completed D. will be completed

17. Had Paul received six more votes in the last election, he_____ our chairman now.
A. must be B. would have been C. shall be D. would be

18. ______ pollution control measures tend to be money consuming, many industries hesitate to adopt them.
A. Although B. However C. When D. Since

19. _______ is often the case with a new idea, much initial activity and optimistic discussion produce no concrete proposal.
A. It B. Which C. As D. That

20. According to the __ of the contract, employees must give six months' notice if they intend to leave.
A. laws B. rules C. terms D. details

21. All of the plants now raised on farms have been developed from plants __ in the wild.
A. once they grew B. that once grew
C. they grew once D. once grew

22. The __ meter can detect even a very small amount of gas in the room.
A. sensible B. sensitive C. sensing D. sensed

23.Not until recent years _______a popular means of communication．
A．e-mail became B．e-mail has become
C．did e-mail become D．Will e-mail become