立式CNC铣床操作完毕后,宜将床台及鞍座置于机器的()。
A、右边;
B、左边;
C、中间;
D、任意位置。
参考答案:C
先化简,再求值:2b2+(a+b)(a-b)-(a-b)2,其中a=-3,b=1.
We ___________ TV at eight o’clock yesterday evening
A. are watching B. were watching C. watched