He failed the final examination and only then ____ how much time he had wasted.
| A．he realized | B．had he realized |
| C．he had realized | D．did he realize |
．It is obvious to the students ______ they should get well prepared for their future.
| A．as | B．which | C．whether | D．that |
．I’m sorry you’ve been waiting so long， but it’ll still be some time ____ Brian gets back.
| A．before | B．since | C．till | D．after |
The house I grew up ________ has been taken down and replaced by an office building.
| A．in it | B．in | C．in that | D．in which |
I invited Mary and Jane to dinner, but of them came.
| A．none | B．either | C．both | D．neither |
．The plant is dead . I ________ it more water.
| A．will give | B．would have given | C．must give | D．should have given |