◎ 题干
       we were playing basketball on the playground, it began to rain.
A.While B.After
C.Before D.Since
◎ 答案
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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“ we were playing basketball on the playground, it began to rain.A.WhileB.AfterC.BeforeD.Since…”主要考查了你对  【实义动词的单数第三人称形式】【实义动词】【动词短语】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。