____ several times, the young scientist still kept on doing his experiments.
| A．Having failed | B．Having been failed | C．Failed | D．To fail |
David knocked at the door for nearly half an hour______Mary opened it, unwilling.
| A．when | B．while | C．until | D．before |
A turning point of the continuously high housing price won’t appear suddenly because there must be a certain process_______many factors lead to the change.
| A．which | B．what | C．where | D．that |
—The trade caused me $500 worth of loss.
--Pity! You didn’t listen to my advice; otherwise, you _________.
| A．would not have taken in | B．might not be cheated |
| C．should not have been taken in | D．would not have been taken i n |
Under the environment of fierce competition, the only way John could imagine____stress was to get tougher by making greater efforts.
| A．handling | B．to handle | C．handled | D．having handled |
The students wonder____good the course will do to their future jobs.
| A．which | B．what | C．whether | D．why |