问题补充：
My sister for long when she fell seriously ill.
A. didn’t marry
B. has been married
C. hadn’t been married
D. wasn’t married
答案：
A. didn’t marry
B. has been married
(答案→)C. hadn’t been married
D. wasn’t married
解析：句意：我姐姐结婚不久以后她就得了严重的病。因为结婚是在生病前发生的，是过去的过去的动作，用过去完成时，选C。
