—Must we keep the window _______ all the time?
—No, you don’t have to.
| A．opening | B．opened |
| C．to open | D．open |
Can you describe the people and the things ______ have been seen in Tibet?
| A．which | B．that | C．who | D．/ |
Now it’s nearly half past six, and we have a little time ______ to catch the last bus.
| A．leave | B．leaving | C．left | D．leaves |
I heard from my pen pal yesterday, but I haven’t replied ______ her.
| A．to | B．for | C．of | D．on |
Did you know ______?
| A．what did they happen | B．what happened to them |
| C．hat they happened | D．what they are happening |
The number of people invited _____fifty, but a number of them ______ absent (缺席) for different reasons.
| A．were; was | B．was; was |
| C．was; were | D．were; were |