—When ___ you ___ the e-dictionary?—Last month.A.have,bought B.had,bought C.do,buy D.did,buy—When ___ you ___ the e-dictionary?—Last month.A.have,bought B.had,bought C.do,buy D.did,buy答案给的是D,但我想知道为什么B不行.

Question

—When ___ you ___ the e-dictionary?—Last month.A.have,bought B.had,bought C.do,buy D.did,buy
—When ___ you ___ the e-dictionary?
—Last month.
A.have,bought B.had,bought C.do,buy D.did,buy
答案给的是D,但我想知道为什么B不行.

Answer 1

应该用过去时,只有表示“在过去的一段时间内”或明确表明“过去的过去”时才用过去完成时.
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