问题 问答题

说明磨床砂轮自动平衡装置的工作原理。

答案

参考答案:砂轮自动平衡装置的结构原理分两类:(1)直角坐标法平衡。是将砂轮的不平衡量分解为在直角坐标轴方向的两个分量,直角坐标法平衡装置的两个配重构成的平衡量分别与不平衡量相平衡。如电磁阀四容腔配水式砂轮自动平衡装置,其配重为由电磁阀控制注入容腔的水量;(2)极坐标法平衡。这种装置是在一轴上装上两半圆的偏心轮,各自可独立缓慢旋转,调整平衡量,根据砂轮的不平衡量,可调整两个偏心轮的相位差和偏重大小,使砂轮平衡。在线砂轮自动平衡装置由平衡头、测振传感器和电气箱的量表组成。

阅读理解

阅读理解。

     "Mom, can I bake some bread?"  We were 15; my best friend, Hanna, and I, determined to try our hands

at creating some beautiful bread.

     "It's not worth the trouble,"  my mother said."It takes lots of time and makes a big mess. Our bakery

bread

is delicious without all that effort."

     Begging was useless. Mom's"no" meant"No!"

     But several weeks later, opportunity knocked. My parents were going out for the evening. I immediately

invited Hanna to be my partner in bread-baking crime.

     We studied the recipe. That was easy. "Mix oil into flour then beat in four eggs, one at a time, with

remaining sugar and salt."

      We were not good at breaking eggs. I tried to learn from my mother.

      "Gradually add eight cups of flour. When dough (面团) holds together, squeeze it."

      We took turns working like that. "Is the dough 'holding together'?"  we asked each other.

      I remembered my neighbor's instructions: "If it's too sticky, add some flour; if too dry, add water."

      We added water. Then more flour. Then more water. By then, the mass of our dough had grown very

much. "Place dough on floured surface and squeeze till smooth,"  the recipe instructed.

     We took turns burying our hands in the damp dough, pinching, squeezing, and feeling it leak between

fingers. "Clean and oil bowl, and then return dough to bowl. Cover and let dough rise in a warm place for

one

hour."

     This was good news-we'd have a break. On the dirty kitchen chairs, we dreamed about our beautiful

bread. "See?" we would tell my mom. "Isn't it worth the work?" 

      Hanna and I couldn't help glancing at the rising process every few minutes. But nothing happened.

     "Maybe something will happen in the hot oven,"  I said.

     Unfortunately, when we removed the loaves from the oven, they were like hard stones.

     Mom was right; it takes time and effort. It sometimes makes a mess. But still it feels good, somehow, to

be part of that long, ongoing chain of bread bakers. Since that night, both Hanna and I have learned to do it

right.

1. To the writer, what her mother said was _____.

A. law

B. rubbish

C. advice

D. warning

2. Which of the following can best describe the children's feelings while making their first bread?

A. Confident; hopeful; proud

B. Curious; hopeful; disappointed

C. Interested; excited; satisfied

D. Worried; satisfied; proud

3. Which of the following did the writer do without referring to the instructions?

A. Placed dough on floured surface.

B. Added eight cups of flour to eggs.

C. Returned dough to a cleaned bowl.

D. Placed the dough into the hot oven.

4. The passage mainly tells us _____.

A. the process of making bread

B. the conflict between mother and daughter

C. the first experience of making bread

D. the way of doing housework

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