на каком расстоянии от линзы надо поместить источник,чтобы изображение находилось на таком же расстоянии от собирающей линзы,что и источник

Закончите уравнения и назовите вещество.

1)CH3-CH2OH--(t>140?,H2SO4)

2)CH3-CH(OH)-CH2-CH3--(t>100,H2SO4)

3)СН3-СН2-CH2OH--(t<100,H2SO4)

4)CH3-CH(OH)-CH3--(t>100,H2SO4)

Решите уравнение:

cosx + cos2x + cos3x = 0

на отрезке .(o;2пи)

About 50 % of people in the United States say that they are shy. And for more than 13 % of Americans, being shy is a serious problem. The situation in other countries around the world is very similar. Of course it is normal to feel a little shy sometimes. Most people feel shy in a new social situation, for example when they start a new job or have to meet and talk to strangers. But in these cases the shyness usually passes quickly.

Some people, however, are extremely shy. They are so shy that they cannot live normally. They feel worried, they sweat and tremble when they are with other people. In order to avoid these unpleasant feelings, the shy person avoids* other people. Shy people often say to themselves: "I'm not normal. People think I am boring and unattractive. I'm a failure." These negative thoughts make it more difficult for the shy person to make friends. The result is that the shy person is lonely and sad.

Shy children need a lot of help. Otherwise these shy children will grow up and become shy, unhappy adults. Parents who have a shy child should set a good example, since children learn a lot of behaviour from their parents. It is also important not to label a child as shy.

Shy children can also help themselves. You have to learn to think positively. You must stop thinking negatively. Another thing you can do is give yourself a target. For example, you may say, "I'm going to talk to at least one stranger today" or "I'm going to ask X to come for a coffee with me." When you achieve your target, you will feel very satisfied. If you are shy, you should try to walk with your head up so that you look at other people's faces. Soon, walking like that will become a habit and you will feel better and more confident as a result.

Of course, it is normal to be shy sometimes. Being a little shy can sometimes stop us from doing things that are foolish. But if you are extremely shy, you do not have to suffer. You can become less shy and become a happy, sociable person.

1. Read the review and say in 2-3 sentences what ut is about.

2. There are quite many shy people in the world and it is not an illness. Read aloud the extract which says about it.

3. Why are shy people sad?

4. What recommendations does the author give parents and children?