问题
多项选择题
下列论述中正确的有（）。
A.零件加工质量的主要指标是尺寸精度和表面粗糙度
B.零件的尺寸公差主要用来限制零件的尺寸误差
C.尺寸公差不可以为负值，也不可以为零
D.零件尺寸公差数值越小，其加工成本越高
E.零件的表面粗糙度主要影响美观，对机器的使用没有什么影响
答案
参考答案：B, C, D
搜题请搜索小程序“爱下问搜题”
下列论述中正确的有（）。
A.零件加工质量的主要指标是尺寸精度和表面粗糙度
B.零件的尺寸公差主要用来限制零件的尺寸误差
C.尺寸公差不可以为负值，也不可以为零
D.零件尺寸公差数值越小，其加工成本越高
E.零件的表面粗糙度主要影响美观，对机器的使用没有什么影响
参考答案：B, C, D
| 阅读理解。 | |||
| |||
| 1. From the first sign we know we can not ______ here. | |||
[ ] | |||
| A. stay for long B. fish C. swim D. go boating | |||
| 2. You'd better ______ if you want to take part in the outing on Sunday. | |||
[ ] |
| A. not go to school B. take your camera C. wear strong shoes D. take the cough medicine |
| 3. If you are hungry at 8:30 am on Sunday, you ______. |
[ ] |
| A. can't get anything from the fast food shop B. can call Jeff on 73338888 C. can go to the fast food shop and buy some food D. drink two teaspoonfuls of cough medicine |
| 4. Helen is nine years old. She's caught a bad cough. She should take ______ a day. |
[ ] |
| A. 1 teaspoonful B. 2 teaspoonfuls C. 1.5 teaspoonfuls D. 3 teaspoonfuls |
| 5. The cough medicine ______. |
[ ] |
| A. can be used by the children aged 3 B. can't be used after October, 2006. C. needn't shake D. can be taken before meals |