-- Has your elder brother returned from Africa yet?
-- Yes, but he _________ here for only three days before his company sent him to Australia.
| A．was | B．has been | C．will be | D．would be |
—Why does the lake smell terrible?
—Because large quantities of water __________.
| A．have polluted | B．is being polluted |
| C．has been polluted | D．have been polluted |
Progress __________ so far very good and we are sure that the work will be finished on time.
| A．was | B．had been |
| C．has been | D．will be |
For many years, people __________ electric cars. However, making them has been more difficult than predicted.
| A．had dreamed of | B．have dreamed of |
| C．dreamed of | D．dream of |
—I'm sorry, but I don't quite follow you. Did you say you wanted to return on September 20?
—Sorry, I __________ myself clear. We want to return on October 20.
| A．hadn't made | B．wouldn't make |
| C．don't make | D．haven't made |
I have to see the doctor because I __________ a lot lately.
| A．have been coughing | B．had coughed |
| C．coughed | D．cough |