A DROP OF BLOOD

Do you know that we have between 250 and 300 million red cells in each drop of blood? As for the white cells[7], there are only about 350 to 500 thousand of them in a drop of your blood so long as you are in good health. But suppose you get an infection – appendicitis, for example. Almost immediately the number of white cells begins to increase until you may have[8] as many as a million and a half in a drop of blood.

The disease germs produce certain chemicals in the body. These chemicals make the white cells divide[9], so that each white cell produces two new cells. The chemicals also stimulate the movement of the white cells toward the place where the germs are causing the infection. Then, when a white cell is close to a germ, it is further stimulated to change its shape. It wraps the germ up. The germ is now inside the white cell, which then starts to digest it. So we can say that the white cells really eat up disease germs. Our blood also has proteins in it. And it has a lot of little cells called platelets, which contain a special chemical. Ordinarily, of course, this chemical stays inside the platelets. But suppose you cut your finger. The blood comes to the surface of the wound and the platelets break down. The chemical is released[10] and it starts to affect the gelatin-like[11] protein in the blood, building a network of fibres. Soon the network is big enough to form a jelly-like stopper for the wound. We say that the blood has clotted and the wound stops bleeding.

Упр. 14. Ответьте на вопросы к тексту:

1. How many red cells are there in each drop of blood? 2. How many white cells do you have in a drop of your blood when you are in good health? 3. Does the number of white cells increase or decrease when you get an infection? 4. What do the chemicals produced by the disease germs do? 5. What does the white cell do when it is close to a germ? 6. What is the name of little cells that contain chemicals clotting the blood?

Упр. 15. Прочитайте следующие правильные глаголы во 2-ой форме (Past Indefinite), обращая внимание на произношение суффикса –ed: после глухих согласных он передает звук [t], после звонких и гласных - [d], после [t] и [d] - [id]:

Asked, worked, kicked, laughed, tried, called, translated, troubled, tied, stopped, walked, saved, destroyed, jumped, helped, wanted, worried, finished, remembered, lived, liked, loved, respected, watched, visited.

Упр. 16. Приведите и запомните 3 формы следующих неправильных глаголов:

Be, begin, buy, come, do, get, give, go, have, know, leave, meet, read, see, send, show, speak, take, teach, tell, think, write.

Упр. 17. Скажите, что Вы (или кто-то другой) делали это же вчера, на прошлой неделе, в прошлом году …:

Модель: - I often write letters to my friend.

- I wrote a letter to my friend on Sunday.

1. I come home at 6 o’clock. 2. I often think about you. 3. My sister teaches Byelorussian. 4. This boy works at his English hard. 5. My son likes ice-cream. 6. Lessons at our school begin at 8 o’clock. 7. I want to see our first teacher. 8. My daughter often asks me this question. 9. We go there every week. 10. I have a dog. 11. I am a sportsman. 12. She is my friend.

Упр. 18. Сделайте предложения отрицательными и вопросительными:

1. She taught at our school two years ago. 2. I knew that. 3. We told you about that. 4. My mother bought a new coat. 5. They showed us his photo. 6. You asked me this questions. 7. He kicked me. 8. They saved a lot of money. 9. You saw many American films last year. 10. You did it on Sunday. 11. She saw you. 12. We met her in Gagarin Street.

Дата добавления: 2015-07-11