造型所用的模样,在单件小批生产条件下,常用什么材料制作()
A.铝合金
B.木材
C.铸铁
参考答案:B
You’d better _______ too much meat. You are much too fat.
A. not eat B. don’t eat C. not to eat
测量过程改变,系统误差的大小和方向都不变。