long enough to have a job, I would choose to be a doctor, hose AIDSpatients．
| A．Had I lived, helping | B．If I should live, help |
| C．Were I to live, helping | D．IfI would live, helping |
By the time you get to Beijing tomorrow, I ______ for Shanghai.
| A．am leaving | B．should have left | C．will leave | D．will have already left |
There is much ______ can be done about the accidents ______ from carelessness.
| A．which, arose | B．that, arising | C．which, arisen | D．that, arise |
The time is not far away ______ modern communications will become widespread in China’s vast countryside.
| A．when | B．as | C．until | D．before |
Most parents encourage their children to take an active part in social events, ______ those events do not interfere with their studies.
| A．concerning | B．until | C．unless | D．provided |
When I try to understand ______ that prevents so many Americans from being happy as one might expect, it seemed to me that there are two causes.
| A．why it does | B．what it does | C．what it is | D．why it is |