— You must keep the door _______ when you leave your room.

— But I want to get the fresh air. I think I can keep the window ________ instead.

A．close, opened

B．open, closed

C．closing, open

D．closed, open

某建筑基坑采用排桩作为支护结构，地下水位与地面相齐，如图所示，坑底用集水池进行排水，土饱和重度γsat=19.0kN／m3。试问：为使基坑底土不致因渗流而破坏，集水池的最小截水长度h（m）最接近下列（）项。（）

A.0.20

B.0.25

C.0.30

D.0.35