（）适用于各类泥石流沟。
A、土埂
B、实体坝
C、格栅坝
D、铁丝石笼坝
参考答案：B
正常成人潮气容积中无效腔气为（）
A.100ml
B.150ml
C.200ml
D.250ml
E.300ml
Before the sales start, I make a list of ______ my kids will need for the coming season.
A．why
B．what
C．how
D．which
