在轴与孔的配合中，采用楔键的表面斜度应为（）。
A.1／20
B.1／30
C.1／50
D.1／100
参考答案：D
You are too___________him. After all he has only been in this field for no more than a year.
A．mistaken about
B．disappointed at
C．particular about
D．sorry for
反渗透装置脱盐率降低的原因和处理方法是什么？
