◎ 题干
Don’t turn off the computer before closing all programs,________ you could have problems.                                                         
A.or B.and
C.but D.so
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“Don’t turn off the computer before closing all programs,________ you could have problems. (2013·北京,22)A.orB.andC.butD.so…”主要考查了你对  【序数词】  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。