多孔插盘装在车床()上,转盘上有12个等分的,精度很高的定位插孔,它可以对2、3、4、6、8、12线蜗杆进行分线。
A.导轨
B.刀架
C.拖板
D.主轴
参考答案:D
下列关于给据邮件表述正确的是()。
A、收寄时出给收据,处理时进行登记
B、投递时收件人要进行签收
C、邮政企业接受寄件人查询
D、邮政企业承担赔偿责任的邮件
The children are having a good time, ______ with sand, others with toys.
A.some of them playing
B.some of them are playing
C.some of them
D.who playing