He asked his father why he was not able to hatch chickens hens could.A. howeverB. whileC.

问题补充：

He asked his father why he was not able to hatch chickens hens could.

A. however

B. while

C. as

D. although

答案：

A. however

(答案→)B. while

C. as

D. although

解析：

试题分析:句意：他问他父亲他为什么不能孵小鸡而母鸡却能。A然而，不管，不论；B然而；C由于，当……时；D尽管。根据句意可知前后句内容是转折关系，故选B。