贯穿推力轴承镜板镜面中心的垂线,称为机组的()。
A.轴线;
B.中心线;
C.旋转中心线;
D.实际中心线;
参考答案:C
It was a pity that when we got to the cinema, the movie___ , so we saw only the end of it.
A.was finishing
B.has just finished
C.just finished
D.had just finished
用科学记数法表示:0.0000012=( )。