你在会上为什么一言不发?误Why did you keep silence in the meeting?
正Why did you keep silence at the meeting?
开会时他对你说了些什么?误What did he say to you at the meeting?
正What did he say to you in the meeting?
析表示“在会上”,应该说at the meeting,其中介词at不可以用in来代替。而表示“在会议期间私下说话”,则应该用介词in,而不用at。