◎ 题干
When he ______ the door, he found his keys were nowhere.  
[     ]
A. would open  
B. opened    
C. had opened    
D. was to open
◎ 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“When he ______ the door, he found his keys were nowhere.[ ]A. would open B. openedC. had openedD. was to open…”主要考查了你对  【不定式】【一般过去时】  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。