Unless to answer questions the pupils won't talk in Mrs Smith's class.A. askingB. asked

问题补充：

Unless to answer questions, the pupils won talk in Mrs Smiths class.

A. asking

B. asked

C. being asked

D. having asked

答案：

A. asking

(答案→)B. asked

C. being asked

D. having asked

解析：B 连词省略句。该句中的unless引导的条件状语从句的主语是the pupils，与主句的主语相同，the pupils与ask之间是被动关系，应该使用过去分词的形式。故B正确。