【判断题】
电弧辐射主要有紫外线、红外线和可见光三种射线,不会产生对人体危害较大的X射线等。
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相关试题
【判断题】
碳孤气刨时,应使用专用碳棒,以免产生过多有害气体。
【判断题】
为了确保氧气瓶的使用安全,出厂前要经受1.15倍瓶装压力的水压试验。
【判断题】
可燃性液体的闪点越低,其火灾危险性越小。
【判断题】
可燃气体钢瓶不许与氧气瓶同车装运或存放于同一库房。
【判断题】
氩弧焊时,电弧的辐射强度比焊条电弧焊强得多,因此,要加强防护措施。
【判断题】
如果需动火的设备处于禁火区内,必须按禁火区的动火管理规定申请动火证。
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发生触电事故后,应立即切断事故发生场所电源开关或插头。
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焊机长期超负荷运行或短路发热会使绝缘损坏而造成焊机漏电。
【判断题】
对于烧伤部位,可以将牙膏、油膏等油性物质涂于烧伤创面以减少创面污染的机会和减轻就医时处理的难度。
【判断题】
纯He气仅用于熔透法焊接,比如焊接铜。
【判断题】
凡与大地有可靠接触的金属导体,均可作为自然接地体。
【判断题】
MAG焊适用于碳钢、合金钢和不锈钢等黑色金属材料的全位置焊接。
【判断题】
铝热焊设备简单、投资少,焊接操作简便,无需电源。
【判断题】
二氧化碳焊可用于汽车、船舶、机车车辆、集装箱、矿山及工程 机械等。
【判断题】
脱离低压电源的方法可用"拉、切、挑、拽"四个字概括。
【判断题】
焊接不带电的金属外壳时,可以不采用安全防护措施。
【判断题】
钎焊作业的安全生产可以消除或控制危险、有害因素。
【判断题】
电子束焊焊接半镇静钢有时会产生气孔,降低焊接速度、加宽熔池有利于消除气孔。
【判断题】
只有将堆焊表面放在倾斜或立焊位置,才能不打渣连续堆焊。
【判断题】
激光切割时,工件和割矩只能有一方运动。
【判断题】
厚板的钨极氩弧焊一般要求填充金属的化学成分与母材不同。
【判断题】
维焊主要用于制造新零件与修复旧零件两个方面。
【判断题】
一辆小轿车上的焊点最多不能超过10000个。
【判断题】
表面堆焊可以采用二氧化碳气体保护焊方法焊接。
【判断题】
埋孤焊时,铁素体、奥氏体等高合金钢,一般选用碱度较高的熔炼焊剂或烧结、陶质焊剂,以降低合金元素的烧损及掺加较多的合金元素。
【判断题】
电子束焊接的焊接速度较低,不如氩弧焊生产效率高。
【判断题】
氢气有最大的扩散速度和很高的导热性,极易漏泄,点火能力低,被公认为是一种极危险的易燃易爆气体。
【判断题】
泡沫灭火剂按泡沫的生成机理可分为三种类型。
【判断题】
在处理保证安全与生产经营活动的关系上,优先考虑财产安全。
推荐试题
【单选题】
The author thinks that people are _________. ___
A. satisfied with their appearance
B. concerned about appearance in old age
C. far from neglecting what is in fashion
D. reluctant to follow the trends in fashion
【单选题】
Fashion magazines and TV advertisements seem to link fashion to _________. ___
A. confidence in life
B. personal dress
C. individual hair style
D. personal future
【单选题】
Causes of fashions are _________. ___
A. uniform
B. varied
C. unknown
D. inexplicable
【单选题】
Present-day society is much freer and easier because it emphasizes _________. ___
A. uniformity
B. formality
C. informality
D. individuality
【单选题】
Which is the main idea of the last paragraph? ______________ ___
A. Care about appearance in formal situations.
B. Fashion in formal and informal situations.
C. Ignoring appearance in informal situations.
D. Ignoring appearance in all situations.
【单选题】
Permissive parents would ________. ___
A. let their children read any books they like to
B. not let their children see any films they like to
C. not let their children read any books without first checking their contents
D. let their children see the films with their first checking
【单选题】
The fact that parents check the contents of the book or the film for their children to read or see shows __________. ___
A. the necessity of censorship
B. that many books and films are bad
C. that children need their parents to help them understand more
D. that the parents are permissive
【单选题】
Which of the following statements is NOT true?____________ ___
A. Some adults can’t tell right from wrong.
B. Censorship is compared to the law because both of them perform good service to society as a whole.
C. Censors pay attention only to genuine works of art.
D. Censorship is necessary because many books, plays and films are far from being “works of art”.
【单选题】
What does the word “corrupt” in Para.4 mean?__________ ___
A. Make morally bad.
B. Hurt.
C. Injure.
D. Damage.
【单选题】
What would be the best title of this passage?_____________ ___
A. Permissive Parents and Responsible Parents.
B. Censorship and the Law.
C. Censors Value Artistic Merits .
D. Censorship Performs Good Service to Society.
【单选题】
Lie detectors are widely used in the United States because _____________. ___
A. they can help detect people’s emotional stress
B. they can help detect people's physiological changes
C. they can help find out whether a person is telling the truth or not
D. they can measure the subject’s electrical resistance
【单选题】
According to the passage, we know that Britain______________. ___
A. will adopt lie detectors widely
B. will adopt lie detectors on a smaller scale
C. adopt lie detectors
D. has not decided whether to adopt lie detectors or not
【单选题】
The tests themselves are by no means free from error..." (Line 1-2.Para.3) means ____________. ___
A. the tests definitely have no error
B. the tests sometimes make mistakes
C. the polygraphers do not make mistakes
D. the polygraphers can avoid error by using some techniques
【单选题】
Which of the following is true? ________________ ___
A. The tests are conducted by qualified polygraphers.
B. Innocent people may blush or stammer when questioned.
C. Guilty people can definitely be found out by answer questions
D. Guilty people may escape by refusing to answer questions.
【单选题】
What troubles lie detector researchers most is that _______________. ___
A. innocent people are convicted crimes
B. innocent people will learn to tell lies
C. lie detectors may cause industrial unrests
D. lie detectors are sometimes not dependable
【单选题】
In the passage the author's attitude towards "mixed-ability teaching" is _______. ___
A. critical
B. questioning
C. approving
D. objective
【单选题】
By "held back" (Line 1) the author means _____. ___
A. made to remain in the same classes
B. forced to study in the lower classes
C. drawn to their studies
D. prevented from advancing
【单选题】
The author argues that a teacher's chief concern should be the development of the student's _________. ___
A. personal qualities and social skills
B. total personality
C. learning ability and communicative skills
D. intellectual ability
【单选题】
Which of the following is NOT MENTIONED in the third paragraph? __________ ___
A. Group work gives pupils the opportunity to learn to work together with others.
B. Pupils also learn to develop their reasoning abilities.
C. Group work provides pupils with the opportunity to learn to be capable organizers.
D. Pupils also learn how to participate in teaching activities.
【单选题】
The author's purpose in writing this passage is to ______. ___
A. argue for teaching bright and not-so-bright pupils in the same class
B. recommend pair work and group work for classroom activities
C. offer advice on the proper use of the library
D. emphasize the importance of appropriate formal classroom teaching
【单选题】
According to the author, the deaths among youth are mainly caused by _____. ___
A. traffic accidents
B. smoking-related diseases
C. murder
D. all of these
【单选题】
Every day there are over_____high school students who will become regular smoker. ___
A. 75
B. 23
C. 30
D. 3000
【单选题】
By "dropout" the author means______. ___
A. students who failed the examination
B. students who left school
C. students who lost their way
D. students who were driven out of school
【单选题】
The reason for declining adolescent smoking is that ________. ___
A. NCI has taken effective measures
B. smoking is prevented among high school seniors
C. there are many smokers who have died of cancer
D. not stated
【单选题】
What is implied but not stated by the author is that ________. ___
A. smoking rates among youth have declined very little
B. there are now more female than male smokers among high school seniors
C. high smoking rates are due to the increase in wealth
D. smokers at high school are from low socio-economic backgrounds
【单选题】
According to the passage, which of the following is NOT a disadvantage of part time education? _______________ ___
A. It requires some break in one's career.
B. It tends to last too long for many people to complete a degree program.
C. It affects one's career.
D. It gives the student less time to share with the family.
【单选题】
Which of the following is NOT an advantage of distance learning? _________ ___
A. The student may choose his or her own pace.
B. The student may study at any time to his or her convenience.
C. They can pursue their chosen career while studying.
D. Their tutorial assistance comes through regular airmail, telephone, etc.
【单选题】
What benefit will distance learning program bring to a business? __________ ___
A. Recruitment of more talented people.
B. Good image of the business.
C. Better cooperation with universities.
D. Further training of employees and business growth.
【单选题】
Good distance learning program have the following characteristic EXCEPT______. ___
A. distance learning course is the same as students taking courses in campus
B. the degree should be same as on campus study
C. professor-student relationship is strictly one to one all through the course
D. includes subject evaluation tool
【单选题】
What benefit will distance learning bring to an employee of a business? ___________ ___
A. Professional growth.
B. Good relationship with the employer.
C. Good impression on the employer.
D. Higher salary.
【单选题】
In the first paragraph, what does "plastic money" (Line 6, Para.1) refer to? ______ ___
A. Dollars.
B. Online payment.
C. Credit cards.
D. Coins.
【单选题】
Which of the following is NOT true about credit cards? ____________ ___
A. Shopkeepers, among others, object to the use of credit cards because they add on the cost of the merchandise.
B. Credit card holders actually pay for their goods after the purchase has been completed.
C. The national company enjoys extensive growth because of the use of credit cards.
D. It has had the effect of increasing consumption.
【单选题】
What is the disadvantage of credit cards? _____________ ___
A. It may lead to the overgrowth of the national economy.
B. The delay in the payment of shopping goods may bring damage to shopkeepers' profits.
C. Some people may intentionally purchase goods that they cannot possibly afford.
D. Those who pay by cash at the purchase will have to pay for the cost added to the product as the interest charge of credit cards.
【单选题】
What is the main topic of the text? ________________ ___
A. Advantages and Disadvantages of Credit Cards.
B. Economic Growth Backed up by the Use of Credit Cards.
C. It can encourage great sums of consumption.
D. Credit Cards Make Life
E. asier.
【单选题】
The author's attitude towards credit card is.______________. ___
A. agreeable
B. neutral
C. humorous
D. oppositional
【单选题】
不含有割地内容的不平等条约是___。
A. 《南京条约》
B. 《北京条约》
C. 《马关条约》
D. 《辛丑条约》
【单选题】
在甲午战争后，严复翻译的《天演论》所宣传的重要思想是___。
A. “师夷长技以制夷”
B. “中学为体，西学为用”
C. “天下兴亡，匹夫有责”
D. “物竞天择，适者生存”
【单选题】
火烧圆明园发生在___期间。
A. 鸦片战争
B. 第二次鸦片战争
C. 甲午战争
D. 八国联军侵华战争
【单选题】
规定允许外国在中国办工厂的条约是___。
A. 《南京条约》
B. 《北京条约》
C. 《马关条约》
D. 《辛丑条约》
【单选题】
1895 年，日本强迫清政府签订___，割去台湾全岛及所有附属岛屿和澎湖列岛。
A. 《南京条约》
B. 《北京条约》
C. 《马关条约》
D. 《辛丑条约》
