问题
选择题
40. —Shall Tom go and play football?
—Not ________ he has finished his homework.
A．when
B．if
C．unless
D．once
答案
答案：C
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40. —Shall Tom go and play football?
—Not ________ he has finished his homework.
A．when
B．if
C．unless
D．once
答案：C
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