用三爪自定心卡盘夹持已加工表面，夹紧力应（）避免工件位移或夹伤工件表面。
A.大些
B.适当
C.小些
D.任意
参考答案：B
The city government is planning to build a factory to deal with the industry waste，but when and where to build it________.
A．haven’t been decided
B．aren’t decided
C．hadn’t been decided
D．hasn’t been decided
喂奶后（）可防止婴儿溢奶。
A、将婴儿横抱数分钟
B、将婴儿轻放在床上，让其尽快入睡
C、将婴儿竖立抱起
D、让婴儿向右侧趴着，轻拍其背部，帮助排出咽下的空气
