Three quarters of the forest ________ burnt to ashes, and the rest _______ cut down for construction.  [ ]

A. was, have been  

B. was, has been     

C. have been, is    

D. has been, are

压力、压差传感器可用于（）的监测。

A、空气压力

B、空气流量

C、液体压力

D、液体流量

E、流体容量