问题
选择题
They kept trying _____ they must have known it was hopeless.
A．if
B．because
C．when
D．where
答案
答案：C
考查连词。if 如果，是否；because因为；when既然，当……时；where在哪儿。句意：考虑到他们一定知道这是没有希望的，他们坚持继续尝试。选C。
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They kept trying _____ they must have known it was hopeless.
A．if
B．because
C．when
D．where
答案：C
考查连词。if 如果，是否；because因为；when既然，当……时；where在哪儿。句意：考虑到他们一定知道这是没有希望的，他们坚持继续尝试。选C。