The scientist has made quite a few discoveries, ______ of great importance to the whole world.
| A．which I think they are | B．which I think are |
| C．I think which are | D．that I think they are |
I was about to tell everyone the truth ______ she turned up.
| A．while | B．when | C．as | D．till |
Helen is on time for everything. How ______ it be that she was late for such an important interview?
A
. might B. can C. must D. may
While you are enjoying yourself in Beijing this time tomorrow, I ______ my mother do housework at home.
| A．am helping | B．will help | C．would help | D．will be helping |
The e-mail, as well as the telephone, ______ an important part in 
daily communication.
| A．is playing | B．have played | C．are playing | D．play |
Jumping out of ______airplane at ten thousand feet is quite _____exciting experience.
| A．/ ；the | B．/ ；an | C．an；an | D． the ; the |