----- Do you know when Tonny came back last night?
----- Yes. It was not yet nine o’clock he came back home.
A. before
B. when
C. that
D. until
网友回答
A. before
(答案→)B. when
C. that
D. until
解析：考查固定句型。句意：当他回家的时候，还没有到9点。A项必须和一段时间连用。选择B项，在nine o’clock前面加at; D项的意思与句子不符。