简述焊缝按照结合形式的分类。

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问题:

简述焊缝按照结合形式的分类。

考点:机械制造行业技能考试金属焊接与切割(综合练习)金属焊接与切割(综合练习)题库
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On the first day of school our teacher let us know someone. Looking out, we found an old woman 16 at the door. She said, “Hi, my name is Susan, I’m seventy years old.” While we were  17 what made her take this challenge (挑战) at her age, she said with a smile, “I'm here to meet a rich husband, get  18 , have two children and travel together.” Hearing this, all of us laughed. “In fact,” she went on, “I always    19 of having a college education, and now I’m getting  20 !”
After class we had chocolate and milk together. We became good  21 . I often listened to this “time machine” as she shared her study with me.
At the end of the term we invited Susan to give us a  22 . When she was stepped up to the front, suddenly she found she took the wrong paper. She felt a little frustrated(沮丧的) and said, “I'm sorry. I’m so nervous that I can’t get my ready talk    23 , so I have to tell you  24 I know .”
In her speech she told us, “We don’t stop playing as we are old, we grow old because we stop playing. The secret of staying  25 , being happy and getting success is that we should laugh and find something  26 every day. I think there is a great  27 between growing old and growing up. I am seventy now. If I  28 in bed for one full year and never do anything. I’ll become seventy – one. Since anybody can grow older, my idea is to grow up by always finding the chance in change. Growing older can’t be avoided(避免的), growing up can be  29 . It’s never too late to be all you can be possible.”
During the four years’ study, it was so easy for Susan to make friends  30 she went. In the end, the wonderful woman got a college degree.
小题1:
A.escapedB.appearedC.reachedD.hurried
小题2:
A.finding B.gettingC.wantingD.wondering
小题3:
A.marriedB.worriedC.excitedD.relaxed
小题4:
A.likedB.madeC.knewD.dreamed
小题5:
A.oneB.eachC.someD.much
小题6:
A.teachersB.friendsC.studentsD.neighbors
小题7:
A.lessonB.presentC.talkD.story
小题8:
A.againB.backC.downD.away
小题9:
A.whichB.howC.whatD.why
小题10:
A.oldB.youngC.clearD.awake
小题11:
A.naturalB.difficultC.interestingD.possible
小题12:
A.differenceB.chanceC.pleasureD.confidence
小题13:
A.lieB.hideC.leaveD.turn
小题14:
A.noticedB.chosenC.thoughtD.mentioned
小题15:
A.wheneverB.howeverC.whereverD.whether
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已知复数z与(z+2)2-8i均是纯虚数,则z等于

A.2i

B.-2i

C.i

D.-i

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当归素是一种治疗偏头痛的有效新药。以下是某研究小组开发的生产当归素的合成路线。

已知:①A的相对分子质量为104,1 mol A与足量的碳酸氢钠反应生成44.8 L气体(标准状况);

②B的结构中含有醛基;

③C在一定条件下生成有机酸D;

④RCHO+HOOC—CH2COOHRCHC(COOH)2+H2O、RCHC(COOH)2RCHCHCOOH+CO2↑。

请回答下列问题。

(1)A的分子式是    ,B的结构简式为    。 

(2)C可能发生的反应是    (填序号)。 

A.氧化反应

B.水解反应

C.消去反应

D.酯化反应(3)反应②的化学方程式为                                    。 

(4)E的名称为    。 

(5)符合下列条件的D的同分异构体共有    种,其中在核磁共振氢谱中只出现五组峰的物质的结构简式为    。 

①苯环上只有两个取代基;

②苯环上的一氯代物只有两种;

③1 mol该同分异构体与足量的碳酸氢钠反应生成2 mol CO2

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内毒素特性

A.强抗原性

B.化学成分为蛋白质

C.细菌的细胞壁裂解后才能游离出来

D.经甲醛处理可脱毒为类毒素

E.60~80℃,30分钟被破坏

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沙漠太阳能计划是在2009年,欧洲与非洲有关企业和机构达成的,目的是在北非撒哈拉沙漠地区建设全球最大太阳能电站。计划投资()亿欧元,于2050年前建成,通过穿越沙漠及地中海的输电线路向欧洲提供每年所需电能的()%。

A、3000;14

B、3000;15

C、4000;14

D、4000;15

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