十字丝中心与物镜光心的连线称为()。
A.横轴
B.竖轴
C.旋转轴
D.视准轴
参考答案:D
27. More and more Chinese women are having difficulty ______ Mr. Right or are choosing the single life.
A.to find
B.finding
C.found
D.in being found
As time _______, we know each other.[ ]
A. goes by
B. passing by
C. went off
D. going by