◎ 题干
—Tom, you look tired this morning. What's wrong?
—I was so busy that I didn't go to bed _______ 12 o'clock last night.
[     ]
A. until
B. when
C. though
D. unless
◎ 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“—Tom, you look tired this morning. What's wrong? —I was so busy that I didn't go to bed _______ 12 o'clock last night. [ ]A. until B. when C. though D.…”主要考查了你对  【介词】  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。