用游标卡尺测量轴的外径时，应使游标卡尺与被测量轴（），并固定锁紧螺钉。

A．平行

B．垂直

C．成一角度

—What do you think of the environment here?  

—Wonderful! _____ of the land _____ covered with trees and grass.      [ ]

A. Two fifths; is

B. Two fifth; are

C. Two fifths; are

D. Two fifth; is