题目内容
There is no way of knowing why one man makes an important discovery ______ another man, also intelligent, fails.
| A．since | B．if | C．as | D．while |
D
解析试题分析：考查连词辨析。A. since因为；B. if 如果；C. as因为；D. while 然而。句意：无法知道为什么一个人有了一个重要发现，而另一个人，同样聪明，却失败了，”“while”是“而，却，但是”的意思，表示转折故选D项。
考点 : 考查连词辨析
Milk will turn sour soon on hot days ______ it is stored in the refrigerator．
| A．since | B．until |
| C．because | D．unless |
Why do you insist on buying a car ______ you have such good public transportation here?
| A．because | B．unless | C．when | D．though |
____ I'm mistaken, I've seen that tall man at a party before.
| A．If | B．As | C．Unless | D．When |
_______ you’ve got a chance, you might as well make full use of it.
| A．Now that | B．After | C．Although | D．As soon as |
It is by no means clear ________ the president can do something to end the strike.
| A．whether | B．which |
| C．that | D．what |
You cannot take back your words _________ they are out of your mouth.
| A．before | B．whether | C．once | D．while |
I have a tight budget for the trip, so I'm not going to fly _ the airlines lower ticket prices.
| A．once | B．if | C．after | D．unless |
Sinking in the cheers of people, David walked off the stage, tears dropping he could stop them．
| A．after | B．when | C．until | D．before |