什么是焊接热影响区?低碳钢焊接时热影响区分为哪些区段?

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问题:

什么是焊接热影响区?低碳钢焊接时热影响区分为哪些区段?

考点:工程材料机械工程材料机械工程材料题库
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过氧乙酸(化学式为CH3COOOH)是一种杀菌能力较强的消毒剂.下列说法正确的是[相 对原子质量:C-12,H-1,O-16(  )

A.它是由碳、氢、氧三种元素组成的

B.过氧乙酸分子中含有氧气分子

C.它的相对分子质量为60

D.碳、氢、氧三种元素的质量比为2:4:3

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Not long ago, a rock band called the Backstreet Boys made a big splash on the music scene. Young people everywhere loved their songs. One of the band’s biggest fans was a young boy named Aaron Carter. Aaron had a special reason for taking such an interest in the band. Nick Carter, one of the Backstreet Boys, was Aaron’s big brother.

Even before Nick joined the band in 1996, Aaron loved music. From the age of two, Aaron spent most of his time listening to the radio. He sang along with his favorite songs. He made up dances to go with them. So Aaron’s family was not surprised when Aaron decided to follow Nick into the music world.

Aaron got off to a fast start. At the age of seven, he joined a band in his hometown of Tampa, Florida. But after two years, Aaron didn’t want to be part of a band anymore. He wanted to sing alone. Soon, Brother Nick gave Aaron a helping hand. During a Backstreet Boys show in Germany, Aaron sang a song. He did an amazing job! After the show, someone from a record company asked Aaron to make an album (专辑). Of course, Aaron said yes!

Since that day, Aaron has made lots of songs that sell well. His songs include “Crush on You” and “I’m Gonna Miss You Forever”.

Aaron has worked hard to become a success. But he never forgets how his brother gave him his start. As Aaron has said, “If Nick wasn’t a singer, then I wouldn’t be there.”

小题1:According to the passage, Aaron _____.

A.joined the Backstreet Boys at the age of seven

B.fell in love with music after Nick became famous

C.was not allowed to sing by his family

D.was thankful for his brother Nick’s support小题2:“Crush on you” is the name of a _____.

A.band

B.song

C.movie

D.play小题3:What does the underlined part “made a big splash” in Paragraph 1 probably mean?

A.Drew wide attention.

B.Got into great trouble

C.Collected a lot of money.

D.Led to a heated discussion.小题4:What is discussed in the passage?

A.The rise and fall of a band.

B.The way to be a singer.

C.The road to success of a singer.

D.The secret of success of a band.

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焦点至工件表面的距离是影响几何不清晰度的原因之一。

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在局麻药中加入肾上腺素的常用浓度是

A.1:1000~3000

B.1:5000

C.1:10000~30000

D.1:200000~500000

E.1:1000000

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人为因素学科的研究对象是()。

A.人与广义环境的相互关系

B.人与人的相互关系

C.人与机器的相互关系

D.人与企业的相互关系

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