Mrs. Smith locked both the front and the back doors before she went to bed（ ）that someone might steal into the house at night.
A、
so
B、
for fear
C、
unless
D、
on condition
【正确答案】：B
【题目解析】：
前半句意为史密斯夫人在睡觉前把前后门都锁了，后半句意为有人晚上偷偷溜进房间。so因此；for fear that 生怕，与原句符合；unless除非；on condition that 如果。句意：史密斯夫人在睡觉前把前后门都锁了，生怕有人晚上偷偷溜进房间。