______ it have been the failure to pick up directions from the ground control that caused the air crash?
| A．Must | B．Could | C．Would | D．Should |
It is none of your business ________ other people think about you.Believe
yourself.
| A．how | B．what |
| C．which | D．when |
—Where's that report?
—I brought it to you ________you were in Mr.Black's office yesterday.
| A．if | B．when |
| C．because | D．before |
You can only be sure of ________ you have at present; you cannot be sure of something ________ you might get in the future.
| A．that; what | B．what; / |
| C．which; that | D．/; that |
Could I speak to ________ is in charge of International Sales，please?
| A．anyone | B．someone |
| C．whoever | D．no matter who |
The traditional view is ________ we sleep because our brain is “programmed” to make us do so.
| A．when | B．why | C．whether | D．that |