题目内容
Bob would have helped us yesterday, but he ________.
| A.was busy | B.is busy |
| C.had been busy | D.will be busy |
A
A [前句表示对过去的虚拟,而but之后表示过去的客观事实,故用一般过去时态。]
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题目内容
| A.was busy | B.is busy |
| C.had been busy | D.will be busy |