---- I followed your advice on how to learn English, but I am still poor in it. Why?

---- Well, ___________.

1. all is well that ends well
2. one man’s meat is another man’s poison
3. no pains, no gains
4. no sweet without sweat

如果不把十字丝调焦到清晰状态，读数将受到（）的影响

A.视准轴误差

B.视差

C.i角误差

D.水平轴误差