数控铣床工作时，所需的全部动作都可用代码表示，（）是用来储存这些代码的。
A、伺服系统；
B、数控装置；
C、控制介质；
D、反馈系统；
参考答案：C
The number of people in the world ________ about 6 billion and large quantities of waste ________
each year. [ ]
A. total; has been produced
B. totals; is produced
C. totals; are produced
D. total; are being produced
术后为什么应早期下床活动？
