精密磨削时,应选用砂轮粒度为()A、40#~60# B、60#~80# C、100#

题型:单项选择题

问题:

精密磨削时,应选用砂轮粒度为()

A、40#~60#

B、60#~80#

C、100#~240#

C、240#~W20

考点:磨工考试磨工考试题库
题型:单项选择题

以下减弱噪声的方法中,属于在声源处减弱的是(  )

A.会场内把手机调到无声状态

B.在飞机旁的工作人员佩带有耳罩的头盔

C.关闭房间的门窗

D.高架道路两侧某些路段设有隔音板墙

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铝箔在氧气中燃烧发生了化学变化,做出这一判断的主要依据是   

A.变化中放出大量的热

B.有白色固体生成

C.看到耀眼的白光

D.铝箔消失了

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盘在地面上的一根不均匀的金属链重30 N,长1 m,从甲端缓慢提至乙端恰好离地时需做功10 J.如果改从乙端缓慢提至甲端恰好离地做多少功?(取g="10" m/s2

题型:单项选择题

阅读下面短文,然后按要求写一篇150词左右的英语短文。

My husband received a letter a month ago a young woman who had been his student when she was in middle school. She was writing because she wanted to thank for having a great influence in her life.

In the letter she wrote,“You were the teacher who helped me discover my talent for math. Before you came to teach us, I had been terribly poor at math, and had never thought that I would be interested in it. To my surprise, you magically showed me the beauty of math. I guess that was the turning point of my attitude towards it. Gradually my interest in it began to grow. Thanks to your encouragement, I made continuous progress in math, and finally made up my mind to study it in the university. Today I am working as an accountant at Valley Medical Center in California. You played an important part.  Thank you!”

What a wonderful gift to a retired teacher! My husband has received many letters from students over the years. This one was special, for it arrived at this time in his life when he is in very poor health.

[写作内容]

1. 以约30个词概括上文的主要内容。

2. 以约120个词就老师影响学生的话题谈谈你的想法,内容包括:

(1)上文使你想起哪位对你帮助最大的老师;

(2)举例说明该老师对你学习或成长的影响;

(3)你怎样看待老师对学生的影响。

[写作要求]

1. 作文中可以使用亲身经历或虚构的故事,也可以参照阅读材料的内容,但不得直接引用原文中的句子。

2. 作文中不能出现真实姓名和学校名称。

[评分标准]

概括准确,语言规范,内容合适,语篇连贯。

题型:单项选择题

若甲产品和乙产品的需求交叉弹性系数为-2,则表明()。

A.甲产品和乙产品都属于生活必须品

B.甲产品和乙产品是替代品

C.甲产品和乙产品都属于抵挡商品

D.甲产品和乙产品是互补品

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