题目

We ____ last night, but we went to the concert instead. A must have studied      B might study C should have studied       D would study 答案：D 解析: They would have bought that house给我们的信息在那时。 D项为陈述语气，陈述当时没有钱这一事实。C应该表达成与过去事实相反的虚拟句If they had had enough money.数据，π，-3，2.5， 中无理数出现的频率是(　 　)A. 20% B. 40% C. 60% D. 80%