题目内容

There were resources such as coal, iron, gold, and copper deep in the soil, but they remained _______.

A. discovered
B. to discover
C. being undiscovered
D. undiscovered

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The president's tone of voice was _______ the students knew that the university authorities tookthe incident seriously.

A. such as
B. so that
C. as such
D. such that

下面哪项不属于表面完整性的内容( )

A. 表面形貌
B. 表面缺陷
C. 表面层物理力学性能
D. 表面加工纹理

利用试切好的工件或采用对刀装置,调整刀具相对工件加工表面位置的方法称为( )

A. 试切法
B. 调整法
C. 尺寸刀具法
D. 自动控制法

机械加工后零件一定深度表面层的物理力学性能与基体材料产生了变化,这个变化的层称为( )

A. 表面烧伤层
B. 表面变质层
C. 表面硬化层
D. 表面过渡层