His sister has become a doctor, ______ is what he wants to be.
| A．who | B．whose | C．that | D．which |
It was found that although the girl could perceive things with her fingers, this ability ceased _____ her hands were wet.
| A．the moment when | B．the moment | C．in that moment | D．before |
______ you understand this rule, you’ll have no further difficulty.
| A．while | B．Once | C．Though | D．Unless |
It will not be long _____man can harness the solar energy and make it serve mankind.
| A．since | B．before | C．when | D．after |
Doing your homework is a sure way to improve your test scores, and this is especially true______ it comes to the classroom tests.
| A．before | B．as | C．since | D．when |
Substances will expand or contract ______ heated or cooled, but this is not the case with water.
| A．when they will be | B．if they will be |
| C．as they being | D．when |