It was very cold. They decided [ ]
A. stay
B. to stay
C. stayed
D. staying
答案：B
地层因素与岩石孔隙度成反比，并随着岩石曲折度的增大而（），但与地层水电阻率无关。
A.减小
B.增大
C.不变
成本-效益分析
