在进行试关井时,必须一边慢关(),一边密切注视()变化。
A、平板阀;
B、节流阀;
C、立压表;
D、套压表。
参考答案:B, D
I suggest that that we should take part in more such activities in future we did yesterday.
A.which
B.as
C.that
D.than
将交叉柱镜的正柱镜轴向与柱镜试片的轴向重合时,被测眼感到比放置前清晰,提示原试片柱镜的焦度()。
A、适量
B、过矫-0.25D
C、欠矫>-0.25D
D、过矫>-0.25D