什么是可编程控制器(PLC)?

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问题:

什么是可编程控制器(PLC)?

考点:仪表工考试仪表维修工中级仪表维修工中级题库
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某地甲、乙、丙、丁、戊五家企业发生了下列生产安全事故。依据《生产安全事故报告和调查处理条例》的规定,其中属于较大事故的有()。

A.甲企业发生事故造成5人死亡,2003万元直接经济损失

B.乙企业发生事故造成2人死亡,11人重伤

C.丙企业发生事故造成15人急性工业中毒

D.丁企业发生事故造成5人重伤,6000万元直接经济损失

E.戊企业发生事故造成55人重伤

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  Dolphins and sharks are showing up in surprisingly shallow water just off the Florida coast.Mullets,crabs,rays and small fish gather by the thousands off an Alabama pier.Birds covered in oil are crawling(爬)deep into marshes(沼泽),never to be seen again.

Marine scientists studying the effects of the BP disaster(英国石油公司漏油事件)are seeing some strange phenomena.Fish and other wildlife seem to be fleeing the oil out in the Gulf and gathering in cleaner waters along the coast in a trend that some researchers see as a potentially troubling sign.The animals.presence close to shore means their usual habitat is badly polluted,and the crowding could result in mass die-offs as fish run out of oxygen.Also,the animals could easily be captured by their enemies.

The nearly two-month-old spill(漏油)has created an environmental disaster in US history as tens of millions of gallons have flown into the Gulf of Mexico ecosystem.Scienfists are seeing some unusual things as they try to understand the effects on thousands of species of marine life.For nearly four hours Monday,a three-person crew with Greenpeace cruised(巡航)past delicate islands and mangrove-dotted inlets in Barataria Bay off southern Louisiana.They saw dolphins by the dozen frolicking(嬉戏)in the oily sheen(光泽)and oil-tinged pelicans feeding their young.But they spotted no dead animals.

“I think part of the reason why we’re not seeing more yet is that the impacts of this crisis are really just beginning,”Greenpeace marine biologist John Hocevar said.

The counting of dead wildlife in the Gulf is more than an academic exercise;the deaths will help determine how much BP pays in damages.

小题1:What do the marine life react to the BP disaster?

A.Dolphins and sharks show up in deep water.

B.Tens of thousands of marine animals are found dead.

C.Sea creatures flee from oil spill,gathering near seashore.

D.Birds crawl(爬)deep into caves.小题2:The environmental disaster was caused by       

A.the lack of environmental sense of BP

B.the nearly two-mouth-old oil spill

C.the crowding marine life

D.the damage of Mexico Gulf ecosystem小题3:What is John Hocevar’s attitude towards the disaster?

A.Disappointed

B.Depressed

C.Neutral

D.Worried小题4:From the passage,we can infer that         

A.marine scientists have seen some strange phenomena.

B.the disaster has little influence on dolphins.

C.a three-person crew reached no conclusion.

D.BP will pay much money according to the number of dead wildlife there.

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电阻可忽略的光滑平行金属导轨,两导轨间距L=0.75m,导轨倾角为30°,导轨上端ab接一阻值R=1.5Q的电阻,磁感应强度B=0.8T的匀强磁场垂直轨道平面向上.阻值r=0.5Q,质量m=0.2kg的金属棒与轨道垂直且接触良好,从轨道上端ab处由静止开始下滑至底端,在此过程中金属棒产生的焦耳热Qr=0.1J.(取g=10m/s2)求:

(1)金属棒在此过程中克服安培力的功W

(2)金属棒下滑速度v=2m/s时的加速度a.

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女性,16岁,14岁初潮,月经期第1天下腹痛最剧,持续2~3天缓解,伴恶心、呕吐,月经持续5天,经血通畅。

应与以下疾病鉴别,哪项除外()

A.子宫内膜异位症

B.处女膜不全闭锁

C.子宫腺肌病

D.残角子宫

E.宫腔粘连

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下面属于被动安乐死的实施办法的是()。

A.注射氰化物

B.口服安眠药

C.放弃治疗

D.注射凝血剂

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