Space exploration began in the 1960s, and since then about five hundred peopleinto space. A.have tra

题目简介

Space exploration began in the 1960s, and since then about five hundred peopleinto space. A.have tra

题目详情

Space exploration began in the 1960s, and since then about five hundred people    into space.
A.have traveledB.traveledC.had traveled D.are traveling
题型:单选题难度:中档来源:不详

答案

A
本题考查时态。根据时间状语since then可知与完成时连用。句意:太空探索开始于20世纪60年代,自从那以后大约有500人游览过太空。

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