第8题: [单项选择]By the time I left the school, the professor ______ that class for two years. A. has taught B. had taught C. will have taught D. will teach 参考答案:B 答案解析:[解析] 本题考查过去完成时的用法。by the time若后接的从句是一般过去时,则主句用过去完成时;若后接的从句表示将来的时间,则主句用将来完成时。根据此原则,“毕业”是过去发生的事情,因此选项B