Scientists say it may be five or six years _______ it is possible to test this m - 高中英语试题 - 超级试练试题库

题目

题型：不详难度：来源：

Scientists say it may be five or six years _______ it is possible to test this medicine on human patients.

A．since	B．after
C．before	D．when

答案

C

解析

此题考查几个时间连词在状语从句中的区别。five or six years 是时间段，就应该找能表示点与点之间关系的连词。since+过去时间点，主句常用现在完成时；after无法确定时间段；when只表点，不表段；所以用before表从现在到测试那一天。

核心考点

试题【Scientists say it may be five or six years _______ it is possible to test this m】；主要考察你对句法等知识点的理解。[详细]

举一反三

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A．since

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