相关试题
【判断题】
U形坡口主要用于焊件厚度较大和重要的焊接构件。
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等离子弧会产生高强度、高频率的噪声,操作者操作时必须塞上耳塞。
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工业用乙炔中因为混有硫化氢及磷化氢等杂质,具有特殊的臭味。
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《安全生产法》规定,生产经营单位对重大危险源可以一劳永逸,不进行定期检测、评估、监控。
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埋弧焊时焊丝的送进速度应与焊丝的熔化速度同步。
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切割分为火焰切割、电弧切割和冷切割三类范。
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LUP-300型及LUP-500型等离子弧粉末焊机便于调节焊接规范。
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钨极气体保护焊使用的电流种类不包括直流正接。
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乙炔瓶内丙酮流出燃烧,不能用泡沫灭火器扑灭。
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电渣焊过程中,可根据需要用水或者停水。
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由于危险源的存在,生产安全事故发生的可能,没特对生广进行安全管理就显得可有可无。
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其他条件相同状态下,人体电阻在干燥与潮湿状态下电阻恒一样。
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厚度较大的焊件,也可选用小功率脉冲激光焊机。
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多丝埋弧焊可以加大熔深并提高生产率,所以得到越来越多的工业应用。
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碳弧气刨的方法设备、工具简单,操作使用安全。
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登高作业时,为防止焊条坠落伤人,应将焊条放在工作服的裤袋内。
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动火管理是为防止火灾和爆炸事故发生而制定的各项规章制度。
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皮肤受强烈紫外线作用时,可引起皮炎、弥漫性红斑,有时出现小水疱、渗出液和浮肿,有灼热感发痒,因此焊接时要注意防护。
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所谓测爆即是查看设备内部的清洁程度和清理程度。
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带压不置换动火只能在连续保持一定正压下才能进行。
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焊接辅助工使用的焊工护目遮光镜片为10号。
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微束等离子弧焊一般采用大孔径压缩喷嘴及联合型电弧。
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可采用模具使堆焊层按模具的形状强迫成形的方法提高于工电弧堆焊的效率。
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埋弧自动堆焊机的焊接速度为无级调节,且焊速稳定。
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当其他焊接不变时,焊丝直径减小,堆焊焊缝熔深增加,熔宽减小。
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焊条电弧焊适用于各种金属材料、各种厚度、各种结构形状的焊接。
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手工电弧焊时产生的热量有一半左右散发在周围空间。
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流量太小,容易变成紊流,使空气卷入,也会降低保护效果。
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附近堆有易燃易爆物品,在未彻底清理或采取有效的安全措施前,不能焊割。
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焊条电弧焊是利用电弧放电所产生的热量将焊条和工件熔化,焊条与工件互相熔合、二次冶金后冷凝形成焊缝,从而获得焊接接头。
【判断题】
氩弧焊引弧所用的高频振荡器会产生一定强度的电磁辐射,接触较多的焊工,会引起头晕、疲乏无力、心悸等症状。
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焊接面有缩孔等缺陷时,应先进行补焊后,才能进行电渣焊。
【判断题】
魏氏组织是一种过热组织,是由彼此交叉约90度的铁素体针嵌入基体的显微组织。
【判断题】
熔化焊与热切割设备运行时,空载电压一般都在50～90V。
推荐试题
【单选题】
When there are no stimuli, a dog will ___________.___
A. wag to the right
B. no wag at all
C. wag to the left
D. wag to the left and then wag to the right
【单选题】
The purpose of doing the experiment is _________.___
A. to train dogs for their owners
B. to help dogs find companion
C. to help people choose their pet dogs
D. to help people judge the mood of dogs
【单选题】
The underlined word "they" in the last sentence refers to __________.___
A. the trainers
B. the systems
C. the researchers
D. the dogs
【单选题】
The new law passed in Rome will ________.___
A. help improve fishing environment
B. stop people from catching goldfish
C. guarantee better conditions for goldfish
D. discourage keeping goldfish at home
【单选题】
People in Rome believe that the civilization of a city can be judged by _________.___
A. awareness of animal protection
B. exchanges with other cities
C. protection of ancient ruins
D. recognition of animal lovers
【单选题】
The underlined word "compassion" in Para 2 is the closest in meaning to __________.___
A. support
B. pity
C. help
D. love
【单选题】
People may break the law in Turin if they ________.___
A. keep their dogs or cats in cars
B. shut their dogs home all day long
C. raise their cats near ancient ruins
D. feed homeless animals in car parks
【单选题】
We can infer from the passage that _________.___
A. the owners can leave their dogs in hot cars
B. the cat only lives in modern life
C. the new law can prevent cruelty to animals
D. the new law gives recognition to the
people who feed homeless cat
【单选题】
If a person finds getting up early a problem, most probably ________.___
A. he is a lazy person
B. he refuses to follow his own energy cycle
C. he is not sure when his energy is low
D. he is at his peak in the afternoon or evening
【单选题】
Which of the following may lead to family quarrels according to the passage?___
A. Unawareness of energy cycles.
B. Familiar monologues.
C. A change in a family member's energy cycle.
D. Attempts to control the energy cycle of other family members.
【单选题】
If one wants to work efficiently at his low point in the morning, he should __________.___
A. change his energy cycle
B. overcome his laziness
C. get up earlier than usual
D. go to bed earlier
【单选题】
You are advised to rise with a yawn and stretch because it will __________.___
A. help to keep your energy for the day's work
B. help you to control your temper early in the day
C. enable you to concentrate on your routine work
D. keep your energy cycle under control all day
【单选题】
Which of the following statements is NOT true?___
A. Getting off to work with a minimum effort helps save one's energy.
B. Dr. Kletman explains why people reach their peaks at different hours of day.
C. Habit helps a person adapt to his own energy cycle.
D. Children have energy cycles, too.
【单选题】
An effective way to prevent the burnout of young athletes is __________.___
A. to increase their sense of success
B. to make sports less competitive
C. to reduce their mental stress
D. to make sports more challenging
【单选题】
According to the passage sport is positive for young people in that __________.___
A. it can help them learn more about society
B. it enables them to find flaws in themselves
C. it teaches them how to set realistic goals for themselves
D. it can provide them with valuable experiences
【单选题】
Many coaches and parents are in the habit of criticizing young athletes __________.___
A. without realizing criticism may destroy their self-confidence
B. in order to make them remember life's lessons
C. believing that criticism is beneficial for their early development
D. so as to put more pressure on them
【单选题】
According to the passage parents and coaches should __________.___
A. help children to win every game
B. pay more attention to letting children enjoy sports
C. train children to cope with stress
D. enable children to understand the positive aspect of sports
【单选题】
The author's purpose in writing the passage is _________.___
A. to persuade young children not to worry about criticism
B. to stress the importance of positive reinforcement to children
C. to discuss the skill of combining criticism with encouragement
D. to teach young athletes how to avoid burnout
【单选题】
As pointed out at the beginning of the passage, people used to think that air pollution _______.___
A. cause widespread damage in the countryside
B. affected the entire eastern half of the United States
C. had damaged effect on health
D. existed merely in urban and industries areas
【单选题】
As to the greenhouse effect, the author ________.___
A. share the same view with the scientist
B. is uncertain of its occurrence
C. rejects it as being ungrounded
D. thinks that it will destroy the world soon
【单选题】
The underlined word "offset" in the second paragraph could be replaced by _________.___
A. slip into
B. make up for
C. set up
D. catch up with
【单选题】
It can be concluded that ____________.___
A. raising the world's temperature only a few degrees would not do much harm to life on earth
B. lowering the world's temperature merely a few degrees would lead major farming areas to disaster
C. almost no temperature variations have occurred over the past decade
D. the world's temperature will remain constant in the years to come
【单选题】
This passage is primarily about __________.___
A. the greenhouse effect
B. the burning of fossil fuels
C. the potential effect of air pollution
D. the likelihood of a new ice age
【单选题】
What is the major function of paragraph 1?___
A. To arouse the reader's concern.
B. To introduce the theme of the whole passage.
C. To summarize the whole passage.
D. To state the primary uses of TV.
【单选题】
Television, as a source of entertainment, is ________.___
A. not very convenient
B. very expensive
C. quite dangerous
D. relatively cheap
【单选题】
Why are some people against TV?___
A. Because TV programs are not interesting.
B. Because TV viewers are totally passive.
C. Because TV prices are very high.
D. Because TV has both advantages and disadvantages.
【单选题】
One of the most obvious advantages of TV is that _________.___
A. it keeps us informed
B. it is very cheap
C. it enables us to have a rest
D. it controls our lives
【单选题】
According to the passage, whether TV is good or not depends on ___________.___
A. its quality
B. people's attitude towards it
C. how we use it
D. when we use it
【单选题】
What regulation was issued by New York State concerning beverage containers?___
A. A fee should be charged on used containers for recycling.
B. Throwaways should be collected by the state for recycling.
C. Consumers had to pay for beverage containers and could get their money back on returning them.
D. Beverage companies should be responsible for collecting and reusing discarded plastic soda bottles.
【单选题】
The returned plastic bottles in New York used to _____________.___
A. be turned into raw materials
B. be separated from other rubbish
C. have a second-life value
D. end up somewhere underground
【单选题】
The key problem in dealing with returned plastic beverage containers is ______________.___
A. how to reduce their recycling costs
B. to sell them at a profitable price
C. how to turn them into useful things
D. to lower the prices for used materials
【单选题】
Recycling has become the first choice for the disposal of rubbish because ______________.___
A. recycling causes little pollution
B. other methods are more expensive
C. recycling has great appeal for the jobless
D. local governments find it easy to manage
【单选题】
It can be concluded from the passage that ____________.___
A. recycling is to be recommended both economically and environmentally
B. local governments in the U.S. can expect big profits from recycling
C. rubbish is a potential remedy for the shortage of raw materials
D. landfills will still be widely used for waste disposal
【单选题】
The author chose to study engineering at a small liberal-arts university because he ________.___
A. intended to be a sensible student with noble ideals
B. wanted to be an example of practicality and rationality
C. intended to be a combination of engineer and humanist
D. wanted to coordinate engineering with liberal-arts courses in college
【单选题】
According to the author, by interacting with people who study liberal arts, engineering students can __________.___
A. broaden their horizons
B. receive guidance in their careers
C. become noble idealists
D. balance engineering and the liberal arts
【单选题】
In the eyes of the author, a successful engineering student is expected ______________.___
A. to be imaginative with a value system to guide him
B. to be a technical genius with a wide vision
C. to have an excellent academic record
D. to be wise and mature
【单选题】
The author's experience shows that he was ________.___
A. creative
B. ambitious
C. irrational
D. unrealistic
【单选题】
The underlined word "they" in "... together they threaten to confuse." (Para.5) refers to ____________.___
A. practicality and rationality
B. engineering and the liberal arts
C. reality and noble ideals
D. flexibility and a value system
【单选题】
It can be learned from the passage that the Ouchidas' house __________.___
A. failed to meet energy conservation standards
B. was designed and constructed in a scientific way
C. is well worth the money spent on its construction
D. is almost faultless from the point of energy conservation
【单选题】
What made the Ouchidas' new house a horrible dream?___
A. Lack of fresh air.
B. Gas leakage in the kitchen.
C. The newly painted walls.
D. Poor quality of building materials.
