I used to feel very nervous when I stood up in front of others, but now I feel quite when

I used to feel very nervous when I stood up in front of others, but now I feel quite when giving a speech to the school．
A. at random
B. at length
C. at ease
D. at sight

A. at randomB. at length(答案→)C. at easeD. at sight解析：考查介词短语：A． at random随意的，B． at length充分地，详尽地，最后，终于C． at ease轻松的，D． at sight一看到…就，一经要求就，一出示就，句意：过去我站在别人前面就感到紧张，但是我现在在学校演讲很放松。选C。

谢谢了