◎ 题干
I will mark________everything you say. It is helpful to the English learners.
[     ]
A. up  
B. down  
C. out  
D. off
◎ 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“I will mark________everything you say. It is helpful to the English learners.[ ]A. upB. down C. outD. off…”主要考查了你对  【介词和介词短语】  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。