问题

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;

正确答案是：

同类题型

It is said that there are ten foreign students in our school. One is from America, _______ is from Australia and all ______ students are from England.

It was raining on the day_______ they arrived.

Hello! There is something wrong with my computer and it can’t work now.— Don’t worry. _____________ What’s your telephone number

Robots will do the simple jobs over and over again, they won’t be bored.

Hurry up! The train _______. You know it _______at 10:00pm.