There’s no way of knowing why one man makes an important discovery another man, also intelligent, fails.
A. since
B. if
C. as
D. while
网友回答
A. since
B. if
C. as
(答案→)D. while
解析:句意:没有办法知道为什么一个人取得重大发现,而另一个人,也很聪明,却不能。since 自从if 如果as 像…… 一样 while 而,却,引导并列句,符合题意,选D。