题目内容
They were surprised that a child should work out the problem ________ they themselves couldn't.
A. once B. then C. While D. if
C
解析:
while(implying a contrast)含相对之意,表示对比转折。
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题目内容
They were surprised that a child should work out the problem ________ they themselves couldn't.
A. once B. then C. While D. if
C
while(implying a contrast)含相对之意,表示对比转折。