Question

【題目】--- I called you last night, but no one answered.

--- Sorry, I _______ sleeping.

A.must have been

B.would have been

C.must be

D.could be

Answer 1

【答案】A

【解析】

考查情態動詞和時態。句意：——昨晚我給你打電話了，但沒人接。——對不起，我一定是睡著了。分析可知，前文提及打電話無人應答，后文解釋原因：肯定當時在睡覺。must have been doing表示肯定當時正在做某事，符合語境要求。C項must be doing表示肯定現在正在做某事，與語境不符。故選A項。