5.What can we learn about the company's new “green” waste management program?
A. The quality of waste management has become worse.
B. The program is becoming more and more popular.
C. Waste management has remained unchanged.
D. More workers are involved in the program.
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( )是用来连接轴和装在轴上的传动零件,起传递转矩作用的常用标准件。
A. 螺栓
B. 键
C. 开口销
D. 弹簧
单个齿轮的规定画法一般用()个视图表达。
A. 一
B. 二
C. 三
D. 四
以下哪项不螺纹最基本的三要素是指()
A. 大径
B. 螺距
C. 旋向
D. 牙型
螺纹按用途可分为紧固连接螺纹、、管螺纹和专门用途的螺纹。