题目

  Our math teacher ______ in our school for 20 years and he _____ here when he was 23 years old.    A. has taught, has come             B. taught, comes    C. taught, came                         D. has taught, came 答案： D 解析:考查动词的时态。for 20 year是现在完成时的时间标志。因此第一空要填has taught；后半句时间状语是when he was 23 years old，动词用一般过去时，因此天came.故答案为D。

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