问题补充:
the reason, it is for sure that yawning can be passed from person to person.
A. Whatever
B. Wherever
C. Whichever
D. However
答案:
(答案→)A. Whatever
B. Wherever
C. Whichever
D. However
解析:考察从句连词选择。Whatever无论什么 ,用语名词前,wherever无论何地,作地点状语 whichever无论哪一个,用于有范围的时候 however无论多么,用语形容词前
句意为,无论是什么原因,可以肯定的是打哈欠是可以从一个人传染到另一个人的。