—Jack can't concentrate on his lessons recently.
—Yes, that might ____ why he did so badly in the last test.
| A．answer for | B．apply for | C．call for | D．account for |
——Hi, Mike．Any idea where Mary is?
——She ____ in the classroom．I saw her there just now.
| A．shall be | B．should have been |
| C．must be | D．might have been |
—Have you thought of the topic for the composition?
— Not yet．I _____ it very carefully, but I haven’t decided.
| A．will consider | B．have been considering |
| C．had considered | D．was considering |
The most important thing about cotton in history is _____ part that it played in ____ Industrial Revolution.
| A．/; / | B．the; / | C．the; the | D．a; the |
People have planted a lot of trees and grass in order to ____ wind and sand in the desert.
| A．hold down | B．hold up | C．hold back | D．hold out |
Read the passage and correct the mistakes, ______.．
| A．if not | B．if any | C．if ever | D．if never |