题目内容
7.Space exploration began in the 1960s,and since then about five hundred people _______ into space.( )A. | are traveling | B. | traveled | C. | had traveled | D. | have traveled |
分析 太空探索开始于二十世纪六十年代,从那时开始,大约有五百人已经进入过太空.
解答 答案:D 题干中since then表示从过去到现在的时间,是现在完成时态的时间状语;句意表达的是已经完成的动作,要用现在完成时态,故选D.
点评 现在完成时表示过去发生的动作对现在造成的影响或结果或表示过去的动作或状态持续到现在.用法有:过去发生的某一动作对现在造成的影响或结果或到现在为止已经发生或完成的动作;表示过去发生的并且持续到现在的动作或状态.
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