15 单项填空【母题来源】【2015重庆卷高考单项填空】【母题原题】【2015重庆】4. If you miss this chance, it may be years _ you get another one.A. as B. before C. since D. after【参考答案】B【命题意图】本题考查了学生的语境理解能力和状语从句的用法。【考试方向】考查before引导的状语从句的用法。【得分要点】连词的辨析一直都是选择题的重点，用法灵活，故切入点就是当时的语境即句意所提供的场景，来判断句子之间的隶属关系；It + will be + 时间段 + before等表示“在之后才”的句型总结一、用于句型“It + will be + 时间段 + before.”句型中，表示“要过多久才”，也可用于“It + may be + 时间段 + before.”，表示“也许要过多久才”。Before 后的句子中用一般现在时态。其否定形式“It will/would not be +时间段+ before”表示“不久就，过不了多久就”。1Jenny, will you leave now?NoIt will be two weeks _ I leave hereAwhile Bsince Cbefore Dwhen【答案】C2Scientists 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考点：考查连词3It was going to be some time _ he would see his father again. A. before B. after C. since D. When【答案】A考点：考查连词