问题 问答题 简答题

什么是死点,如何判断死点的位置?

答案

参考答案:

主动机构全部组装后由于曲轴上两曲拐方向相差90°,汽缸勾贝的位置则相差半行程,如果我们将往复运动机件在前后两个终端的位置吊行程极端,而将做圆圈运动前后两个极点叫做死点(严格地说,死点应是曲拐圆周运动轨迹与汽缸中心线的两个交点)

阅读理解

阅读理解

     Much as Robby tried, he lacked the sense of tone and basic rhythm (节奏). But he dutifully reviewed

his lessons. Over the months he tried and tried, and often repeated to me "My mom's going to hear me

play some day."

    But he seemed hopeless, with no born ability. A real bad advertisement for my teaching! I was so

happy when one day he stopped coming.

    Several weeks later my students were to have a recital (演奏会). To my surprise, Robby came, asking

to play in the recital.

     "But, it is for current pupils; you dropped."

     "My mom was sick. But I have been practicing. I've just got to play!"

    I didn't know what led me to agree, maybe...

    The recital came. I__put__Robby__up__last__to__play__before__my__"curtain__closer", by which,

I could save the recital if...

    The recital went on well.  Robby came up on stage, clothes wrinkled and his hair looked like he'd run

an eggbeater through it. "How could his mom...?"

     Robby pulled out the piano bench and began. It was Mozart's work! I was not prepared for what I

heard next. Like in a dream, I was then woken up by the wild applause-everybody was on their feet!

     "I've never heard you play like that, Robby! How'd you do it?"

    Through the microphone Robby explained: "Well, Miss Hondorf, remember I told you my mom was

sick? Actually she had cancer and died this morning. She was born deaf, and tonight was the first time

she ever heard me play. I wanted to make it special."

     My eyes were wet. He was not a student of mine, but a teacher!

1. We can infer from the underlined sentence that the writer ________.

A. was fully confident that Robby would perform well in the recital

B. thought that Robby would make the recital special

C. thought that Robby wouldn't play in the recital

D. had no confidence in Robby at all in the recital

2. What made the boy succeed in the recital?

A. Love for his mother.    

B. Musical talent.

C. The writer's help.      

D. Regular practice.

3. What made the writer think that Robby was her teacher, not a student?

A. That he played better than her in the recital.

B. That he loved his mother more than she did.

C. That he never gave up.

D. That the audience gave him more applause than her.

4. What is the highlight of the recital?

A  The writer's performance.

B. Robby's performance.

C. Robby and his mom's story.

D. The audience's applause.

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