题干

如图所示的空气压缩机,当储气罐内的压缩空气排放到一定程度 时,压力开关自动接通电源,电机带动气泵运转,向储气罐补充 压缩空气,使储气罐内的气压保持在设定范围内。下列关于该压 缩机的气压控制系统分析中,正确的是

A:控制方式属于开环控制

B:输入量是电能

C:控制量是气泵输出的空气流量

D:输出量是储气罐内的压缩空气

上一题 下一题 0.0难度 选择题 更新时间:2010-10-14 11:30:16

答案(点此获取答案解析)

C

同类题1

阅读理解

Drug problems

    If you're worried about your own or someone else's drug taking or misuse, it's good to know the facts.

Why take drugs?

    Drug users don't start using drugs with the intention of becoming addicted. But many drugs contain addictive substances(物质) and even people who use them occasionally can become dependent and need to use them regularly.

    Reasons why people start using drugs can include: to escape problems they may be having in other parts of their life, peer pressure and fitting in with another group of people, being curious about the effects of drugs.

    If you start to use drugs on a regular basis, or if you become dependent on them, it can affect your family and friends as well as having a serious impact on your own physical and mental well-being.

    Drug overdoses can be fatal. You can die instantly from misusing substances and drugs that you can buy over the counters.

Signs of drug abuse and misuse

    There is not a common list of symptoms that you can use to tell if you or someone you know is misusing drugs. That's because drug use affects different people in different ways, depending on the type of drugs they're using.

    Although anxiety, tiredness and a change in sleeping habits can be signs of drug use, they can also be caused by changes in your body, stress or other problems.

_____________________

    Drugs are categorised into three classes based on their overall level of harm. Class A drugs are the most dangerous, however, all the drugs in all three classes are harmful and addictive.

    Remember that all drugs are illegal, even Class C drugs like cannabis(大麻烟). If you're caught selling them to other people, or carrying a small amount in your pocket, it's likely that the police will get involved.

    If you're found guilty of any of these offences, you may face a fine or time in custody(拘留), with Class A drugs carrying the most severe sentences.

Worried about a friend?

    If you think that one of your friends or relatives is misusing drugs, you may want to approach them and talk about it. It's not your responsibility to make them stop, but you can tell them about how their behaviour is affecting your relationship.

    If they ask for help with their problem, then it's important to listen and help them find the right information and treatment.

National Drugs Helpline

    If you're worried about drug abuse and addiction you can call the National Drugs Helpline on 0800 776 600 for confidential advice—lines are open seven days a week. Calls are free and they won't show up on your phone bill, but you may be charged if you use a mobile.

More useful links

Information about addictions from need to know

Information about drugs, the law and human rights