◎ 题干
I'm sorry that I have kept you _________ outside for so long.
[     ]
A. standing          
B. stand
C. to stand            
D. to be standing
◎ 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'm sorry that I have kept you _________ outside for so long.[ ]A. standing B. standC. to standD. to be standing…”主要考查了你对  【分词】  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。