机床夹具主要功能是使工件相对（）和（）保持正确相对位置。
参考答案：刀具；机床切削
句型变换。
1. That is his sister. (改为一般疑问句)
_______ _______ his sister?
2. Mike is fine. (对划线部分提问)
_______ _______ Mike?
3.This is my watch. (改为复数形式)
_______ are my _______ .
4. Those are my brother's computers. (改为否定句)
_______ _______ my brother's computers.
5. photo, here,family,is my, a, of (连词成句)
_______________________________________.
第一部机动战士高达的监督是（）
