单选题 What is in the drug that makes you sick or dead? 1 , cocaine is harmful, but what makes it harmful?
I can"t tell you about drugs, but I can help you think about them in this simple way. Your body is a very 2 machine, really a lot of chemical machinery, all of which 3 so that it all works together. Special 4 , which we call drugs, can affect it or 5 it in many different ways.
Some drugs are 6 when your body has a problem, 7 disease-causing bacteria. Then someone may give you aspirin to keep your temperature from going too 8 or some penicillin because it stops the growth of some kinds of bacteria. 9 , all drugs are really poison, 10 if you take too much, so you must always use them carefully.
Why do some people take drugs like cocaine? For a little while they seem to make you feel 11 , or smarter, or happier. But after their effects have worn 12 , your body has to pay an extra 13 to get back to 14 . That makes you want to get some more of the drug. So we say they are addictive.
Drugs like cocaine have their special effects 15 they act as special poisons for your nervous system. They disconnect some of your nerve pathways and take 16 some of your senses and your worries. They make you want always more. And just a little 17 much can even block nerves to your heart and stop its beating.
Many of us worry about the environment around us and what pollution does to 18 How about your internal environment, and what 19 inside you? You control that all by yourself in what you put into your 20 . Most drugs are pollutants. You would not want pollutants in the air and water around you. Why would you want pollutants in your body?