定向井在0°～45°时最好选用（）。
A、层流
B、紊流
C、柱流
D、任意
参考答案：A
As a result of the serious flood, twothirds of the buildings in the area ________. [ ]
A. need repairing
B. needs to repair
C. needs repairing
D. need to repair
黏性土压实参数包括（）
A.铺土厚度
B.压实遍数
C.压实时间
D.含水量
