第30题: [单项选择]--"I bought this shirt for 35 yuan yesterday." --"It's on sale today for only 29. You should have waited." --" Oh, really But how _________ I know." A. could B. did C. can D. do 参考答案:A 答案解析:[汉译] 一昨天我花了35元买了这件衬衫。
—你应该再等一等,这件衬衫打折了,今天才卖29元。
—真的吗 但是我怎么可能知道它会打折
[注释] 情态助动词CAN的过去式COULD,用于表示不确