问题
选择题
Why did they keep trying _________ they must have known it was hopeless?
A．if
B．because
C．when
D．whether
答案
答案：C
这题考查连词的用法，when表示“既然”句意是：既然他们已经知道是无望了，为什么还要一直尝试呢？选C。
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Why did they keep trying _________ they must have known it was hopeless?
A．if
B．because
C．when
D．whether
答案：C
这题考查连词的用法，when表示“既然”句意是：既然他们已经知道是无望了，为什么还要一直尝试呢？选C。