[originaltext] To help ourselves and others, it’s important to know somethin

To help ourselves and others, it’s important to know something about drugs. A drug is a chemical substance. It can bring about a physical, emotional, or mental change in people. Alcohol and tobacco are drugs. Caffeine, a substance found in coffee and some soft drinks, is also a drug.
    Drug abuse is the use of a drug, legal or illegal, that hurts a person or someone close to him. A drug user is the person who takes the drug. There are many kinds of drug users. Experimental users may try drugs once or twice. They want to see what the effects will be. Recreational users take drugs to get high. They use drugs with friends or at parties to get into the mood of things. Regular users take drugs all the time. But they are often able to keep up with the normal routine of work. Dependent users can’t relate to anything but drugs. Their whole life centers around drugs. They feel extreme mental or physical pain without drugs.
    It’s not always easy to tell that someone is using drugs. In the early stages, drug use is often hard to see. Sometimes, people like drugs or need drugs so much that they can’t do without them.
They are dependent upon drugs. Only a few kinds of drugs can cause physical dependence. But almost any drug, when it’s misused, can make a person think he needs it all the time. By this time, it’s too late and the person is hooked.
Questions 16 to 18 are based on the passage you have just heard.
16. What does the speaker say about drug abuse?
17. What does the speaker say about recreational drug users?
18. What does the speaker say about drug dependence?