◎ 题干
I have been living in the United States for twenty year, but seldom _____ so lonely as now.
[     ]
A. have I felt
B. I had felt
C. I have felt
D. had I felt
◎ 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 have been living in the United States for twenty year, but seldom _____ so lonely as now. [ ]A. have I felt B. I had felt C. I have felt D. had I felt …”主要考查了你对  【现在完成时】【部分倒装】  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。