--- He worked out such different questions at a very young age.
--- Oh, he ______ a very smart student then.
| A．could have been | B．should have been |
| C．might have been | D．must have been |
She pretended __________ me when I passed by.
| A．not to see | B．not seeing | C．to not see | D．not see |
The old couple has two children, __________ able to come to see them when they feel lonely, however.
| A．both of them are | B．neither of them are |
| C．none of whom are | D．neither of whom |
I found I could easily make myself _________ by using sign language.
| A．understood | B．understand | C．to understand | D．being understood |
Shall I tell him the change of the schedule right now?
---- I am afraid you ________, in case he comes late for the meeting.
| A．will | B．must | C．may | D．can |
We came to a house ________stood a tall tree
| A．which before | B．in front of which | C．on which | D．in which |