题目内容
_____ Monday morning he wrote an article on grammar.
_____ Monday morning he had written an article on grammar.
_____ Monday morning he had written an article on grammar.
| A.By | B.On | C.At | D./ |
B
A.用on(at)+过去时间状语,句子用过去时;by+过去时间状语,句子用过去完成时.
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