the doctor asked me how long i ___ form headache. A.suffer B.am suffering C.have suffered D.had suffered 选什么 给个理由. 谢谢.
问题描述：
the doctor asked me how long i ___ form headache. A.suffer B.am suffering C.have suffered D.had suffered 选什么 给个理由. 谢谢.
答
D how long 应用现在完成时,但前面有 asked ,时态应一致,所以往后退一格,用过去完成时所以往后退一格，是什么意思啊has done....had donedo....didwill.....do以此类推