题干
By the time they reached the bus stop, the bus__________ for ten minutes.
A：had left
B：have left
C：had been away
D：have been away
答案(点此获取答案解析）
C
By the time they reached the bus stop, the bus__________ for ten minutes.
A：had left
B：have left
C：had been away
D：have been away
”是“sin α＝1”的充要条件；
4的展开式中的常数项为2；
－p.其中所有正确命题的序号是( )．
