软土地区城市地铁隧道施工时,应优先选择的盾构类型有()
A.手掘式盾构
B.半机械挖掘式盾构
C.机械挖掘式盾构
D.土压盾构
E.泥水盾构
参考答案:D, E
羽毛球单打比赛一局结束后,下一局开始时,由上一局的()发球。
I don't know ______ that kind of materials. [ ]
A. where to buy
B . what to buy
C. when I
D. why you buy