问题
单项选择题
No sooner had we reached the top of the mountain ______ we all sat down to rest.
A. when
B. then
C. than
D. until
答案
参考答案：C
解析： no sooner...than...“一……就……”引导时间状语从句，主句用过去完成时，than后面的从句用一般过去时，no sooner...than...常放在句首，表示强调，这时主句要倒装。故选C。