杂质的生成能增高己内酰胺成品的消光值。
参考答案：对
---I did very well in the Maths exam yesterday.
---I did _____ . I got full marks.
A．no better
B．no worse
C．even worse
D．not better
用于两相分轴之间的传动为（）
A.圆柱齿轮
B.圆锥齿轮
C.蜗轮蜗杆
D.皮带
