题干
— Shall Brown come and play computer games?
— No, ________ he has finished his homework.
A：when
B：if
C：unless
D：once
答案(点此获取答案解析）
C
— Shall Brown come and play computer games?
— No, ________ he has finished his homework.
A：when
B：if
C：unless
D：once
的定义域为（ ）
