20. When Jack arrived, he learned Mary ____ for almost an hour.
| A．had gone | B．had set off | C．had left | D．had been away |
It was so dark in the cinema that I could hardly __________ my friend.
| A．turn out | B．bring out | C．call out | D．pick out |
Theydidn't know _________ to do with themselveswhen the project was finished.
| A．how | B．when | C．what | D．where |
The temperature in spring here can drop __________ below zero.
| A．by | B．from | C．with | D．to |
The meeting __________ three hours last night, which made us very tired.
| A．covered | B．had | C．lasted | D．referred |
If you are worried that the tickets will be sold out, you can buy one __________.
| A．in time | B．in advance | C．on time | D．from time to time |