For a long time, he hesitated whether he should tell us what had happened.
A. at dusk
B. at length
C. at present
D. at stake
网友回答
A. at dusk
(答案→)B. at length
C. at present
D. at stake
解析： 考查短语辨析。at dusk在黄昏，at length最后，详尽地，at present现在，at stake生死攸关，句意：很长一段时间，他犹豫是否他应该详尽地告诉我们所发生的事。故选B。