Question

【题目】--- 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】

考查情态动词和时态。句意：——昨晚我给你打电话了，但没人接。——对不起，我一定是睡着了。分析可知，前文提及打电话无人应答，后文解释原因：肯定当时在睡觉。must have been doing表示肯定当时正在做某事，符合语境要求。C项must be doing表示肯定现在正在做某事，与语境不符。故选A项。