原始误差
参考答案：
由机床，刀具，夹具，和工件组成的工艺系统的误差。
A good friend of mine from ________ I was born showed up at my home right before I left for Beijing.[ ]
A. how
B. whom
C. when
D. which
合同的成立，需要经过（）和承诺两个阶段。
