2. 1

3. 2 Cloning: Advantages: 1. can help some women have babies 2. can help medical research Disadvantages: 1. it is not natural to make people 2. dangerous; people use it to do strange things

4. 3 Nuclear energy: Advantages: 1. can make all the electricity we need 2. is a limitless resource Disadvantages: 1. unsafe to all life if not controlled 2. can be expensive to build / repair

5. 4 Computers: Advantages: 1. makes communication faster 2. can keep information better Disadvantages: 1. unsafe because of viruses 2. makes more problems than it solves

6. 5 Space flights: Advantages: 1. makes research of outer space possible 2. put communication satellites in space Disadvantages: 1. expensive and dangerous 2. used by the army

7. 6

8. 7 Cloning: A: Cloning is one of the most important discoveries of our times. B: I think it should be forbidden. It’s dangerous and it’s unnecessary. A: What do you mean? It ’ s great if we can clone people. It ’ s a way to make people, so women can have babies but they don ’ t need to give up their jobs.

9. 8 Cloning: B: But don ’ t you think it ’ s wrong to sort of make people? It ’ s unnatural. And besides, some people will use it for other things. A: I don ’ t think so. Cloning can be useful to the development of medicine and make the life of women more comfortable. B: No. You should think of the dangers. People will use it to create people and use those people as slaves.

10. 9 Nuclear energy: A: It ’ s been known for many years that we can ’ t go on using coal and oil for fuel. They pollute the environment too much. Nuclear energy is the best way to make electricity. It’s clean and it doesn’t pollute the air. It can help many people in the future. B: It ’ s true that it doesn ’ t pollute the air, but it isn ’ t clean. Nuclear waste is very dangerous for your health. Accidents in nuclear energy plants can kill all life on the planet. These places aren ’ t really safe you know.

11. 10 Nuclear energy A: I think you worry too much. Electricity from nuclear energy is cheap and that is good for the economy. B: I don ’ t believe it can be cheap. These factories are very expensive to built, to keep working safely and taking care of their waste is also very expensive. Nuclear waste is very bad for the environment. A: Well. What do you want to use instead of coal and oil for fuel? B: Nuclear energy is unnecessary. People can use water power and the sun to make electricity.

12. 11 Computers: A: Computers are very useful and can help people in the future even more. B: I agree. But there are also disadvantages. A: What do you mean? B: Well. Just think about it. Who makes computers? People do. Right? And because the people who make computers can make mistakes, we can ’ t rely on computers. A: I see your point. But what problems will they cause? B: Who knows? Maybe they will make people lazy. Maybe they’re unnecessary for doing some jobs.

13. 12 Computers: A: I don ’ t agree that they ’ re unnecessary. I think computers are important for science, especially for medicine. There is no doubt about it. Computers can store a lot of information and it ’ s very easy to find information. With computers people can work faster. Today one man working with a computer can do the job of ten people in the past. That’s good for the economy. B: That ’ s true, but for common people they’re still too expensive. A:I agree. But I ’ m sure they ’ ll become cheaper. In the future we ’ ll all be using computers every day, and they’ll bring people more comfort.

14. 13 Space flights: A: China is the third country in the world that has sent a man into space. Isn ’ t it Great! B: Yes. It ’ s a great achievement. I ’ m sure it’s very important for science, but on the other hand, such space flight are very expensive. A: That ’ s true. But you mustn ’ t think of it in that way. Think of all the new discoveries that will be made during space flights! It can help many people in the future. China can put satellites up into space that we need for communication.

15. 14 Space flights: B: Well. I still think they ’ re too expensive. The space programme costs too much money and that money could be spent better on other things. Besides, I ’ m sure these discoveries you are talking about can also be made on earth. So space flights are unnecessary. A: Well. Aren ’ t you proud of our nation ’ s space programme? B: Sure I am. But that does not change my mind about the advantages and disadvantages of apace flights.

16. 15

17. 16 Physics Madame Curie (Radioactivity) Isaac Newton (gravity) Lord Kelvin (lowest temperature) Medicine Florence Nightingale (pie charts) John Snow (spread of disease) Louis Pasteur (germs)

18. 17 Chemistry Watson & Crick (DNA) Gay-Lussac (Gas laws) Mendeleev (Periodic Table of elements) Biology Beatrix Potter ( “ seeds ” of mushrooms) Charles Darwin (Evolution) Carl Linnaeus (Naming plants)

19. 18 True or false:  1. In 1752, scientists already know what electricity is.  2. Franklin was helped by a friend to do the experiment.  3. Franklin made the kite of silk because wet silk doesn ’ t conduct electricity.  4. A condenser was used in the experiment to store electricity.  5. The key tied to the string was put into the door to stop the kite from flying away.

20. 19

21. 20 You are in a thunderstorm Does If you are outdoors, go home or to a safe place as quickly as possible. Stay indoors if you are at home. Take shelter in a big building. Close the windows if you are in a car. Keep your body low to the ground. Make yourself as small as possible.

22. 21 You are in a thunderstorm Don ’ ts Don ’ t shelter in small buildings. Don ’ t shelter under trees that stand alone. Don ’ t use the telephone. Don ’ t use electrical machines. Don ’ t take a bath or shower. Don ’ t use the air conditioner.

23. 22 Physics experiment Dos Be on time before the experiment starts. Carefully follow all instructions. Pay attention to safety both of yourself and others. Check all instruments before starting to see if they are OK. When the experiment is over, the students should put the instrument in order. Keep the lab clean.

24. 23 Physics experiment Don ’ ts Don ’ t touch the instruments before the experiment starts. Don ’ t leave the lab without the teacher ’ s permission. Don ’ t take anything from the lab.

25. 24 Hiking trip Dos Wear good shoes and clothes. Bring a backpack Tell someone where you are going. Bring water and a map. Watch out for dangers such as snakes. Wear a hat. Bring a cellphone.

26. 25 Hiking trip Don ’ ts Don ’ t go alone. Don ’ t take unsafe roads. Don ’ t put your life in danger. Don ’ t go on if you aren ’ t feeling well.

27. 26 Chemistry experiment Dos Keep chemicals and instruments in order. Keep quiet in the lab. Keep the instruments clean and dry. Put away all instruments when the experiment is over. Shut the windows, turn off the lights, tap and gas and lock the door before leaving the lab. Save water, electricity and chemicals. Take good care of the instruments and other items in the lab.

28. 27 Chemistry experiment Don ’ ts Don ’ t speak loudly. Don ’ t walk around if you don ’ t have to. Don ’ t touch instruments unless you know how to use them. Don ’ t take the instrument apart. Don ’ t be late for the experiment. Don ’ t leave class without the teacher ’ s permission.

29. 28

30. 29 n. + n. → n. cupboard doorbell salesgirl baseball farmland teamwork keyboard spaceship sunglasses workplace schoolyard moonlight seafood

31. 30 adj. + n. → n. best-seller loudspeaker mainland greenhouse

32. 31 adj. + n. → adj. halfway part-time second-hand

33. 32 prep. + n. → adj. outdoor outside underground upstairs undersea

34. 33 Answers to the questions: 1. Brown ink is a mix of different colours of ink. When separating these colours, they suddenly com out. When we could not see them, it seems as they were “ hidden colours ”. 2. The colour green is made by mixing yellow and blue. The colour orange is made by mixing red and yellow. The colour purple is made by mixing red and blue. 3. The water should not touch the ink dot because then the ink would get into the water, and the results of the experiment would not be clear.

35. 34 Answers to the questions: 4. If the experiment does not work, and the ink does not “ travel ” up the paper strip then there can be two reasons: 1 The ink from the makers does not go up with the water.(The ink is not water soluble.) 2 The paper is not good for this experiment (The paper either does not let the water through or lets the water through too fast.) 5. The police can use this technique by separating liquids such as blood or urine to check whether they contain drugs or poison.