◎ 题干
Mr. Li               swimming for 3 hours, and his son              an hour ago.
[     ]
A. has been; started
B. have started; has started
C. started; started
D. has started; has started
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“Mr. Liswimming for 3 hours, and his son an hour ago. [ ]A. has been; started B. have started; has started C. started; started D. has started; has start…”主要考查了你对  【一般过去时】【现在完成进行时】  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。