Astronauts are not like pilots, who fly into sky. They need some special trainings. They will fly into space. First they go to the Johnson space center in Houston Texas. They are tested there. Space doctors want to know how strong and smart they are.

      First of all, their hearts are tested. The people walk or run. Next, the space doctors see how fast their hearts are beating.

      Then it is another important test. In this test the person must curl his body up in a ball. And when he is in that position, he will be put into a round cloth bag. The doctors don't tell him how long he will have to stay in the bag. If a spaceship broke down in space, the astronauts would get into bags like these. Then they would have to wait, curled up in darkness, until they are saved. You can know that an astronaut must not be afraid of tight spaces or darkness.

      After these tests, scientists only choose the best people to start astronaut training in a training center. They will learn many other things in training. They will learn how to jump out of moving airplane, to blow up a lifeboat and get into it while they are in the ocean.

They also have to learn how to get lifted out of the ocean by a helicopter.

      When they finish training, the astronauts go on to work. They stay in good situation by running and doing exercise. They read about the special jobs. In that way they will be able to learn new facts about space travel.

      Finally, the astronaut is told to go to work on a flight into space. The members begin to know each other first. Then they can learn which jobs each will do.

    Harmful microbes like bacterias, viruses and other germs are pathogens. They may enter your bodies and make you ill. The immune system is the body's defence system that protects you from illness and disease caused by the pathogens.

    The immune system is made up of non﹣specialized defences such as skin, tears and the acidic juice produced by the stomach, keeping you from the pathogens. It also has some highly specialized defences, which are different kinds of immune cells, grouped into phagocytes and lymphocytes. Phagocytes are a type of white blood cell. They are swimming around in your blood stream, always on the lookout for antigens﹣the pathogens that have entered your bodies. Whenever they see one, their will eat it. However, some antigens are hard to find and kill. Then lymphocytes, which are also white blood cells and the main types are B cells, T helper cells and T killer cells, Will be the killers of the sneaky antigens.

    B cells, T helper and T killer cells work together to find and kill these antigens. B cells produce substances, called antibodies, which stick to the antigen. When that happens, it will tell the T helper cells to come over and either: 1. help the B cells kill the antigen, or 2. call the phagocytes or T killer cells to move in for the kill. Once a B cell or a T cell attacks an antigen, they create cells to "remember" it. Those "memory cells" hang out in your blood if they see the same antigen again, they quickly recognize, it so your immune system can act faster at killing it.

    The immune system is more powerful than you probably imagine. Scientists from the University of Pennsylvania recently took immune cells from three patients with leukemia, then genetically changed them into "serial Keller "cells to attack cancer cells. The study was small but the results were groundbreaking. The modified immune cells increased at least 1, 000 times in the body and killed all the cancer cells. Therefore, more "memory cells" were created.

    The immune system can be developed. Eating lean protein food （beef, beans ）and food rich in vitamins A, C, and E（sweet potatoes, carrots ）, taking a 30﹣minute walk every day and reducing your stress levels, etc. will help you achieve it.

D

    Research proves that nearly half of the cancers diagnosed(诊断) in the UK each year-over 130, 000 in total- are caused by life choices that include smoking, drinking and eating the wrong things.

    Tobacco(烟草) is the biggest factor, causing 23% for cases in men and 15.6% in women, says the Cancer Research UK report. Next comes a lack of fresh fruit and vegetables in men's diets, while for women it is being overweight. Lead author of the report, Professor Max Parkin, said: "Many people believe cancer is related to fate or in the genes(基因), and that it depends on luck whether they get it or not. Looking at all the evidence, it is clear that around 40% of all cancers are caused by things we mostly have the power to change."

    For men, the best advice appears to be: stop smoking, eat more fruit and vegetables and cut down on how much alcohol you drink. For women, again, the best advice is to stop smoking, but also watch your weight.

    In total, 14 lifestyle and environmental factors, such as where you live and the job you do, cause 134, 000 cancers in the UK each year.

    Some risk（风险） factors are well founded, such as smoking's link with lung cancer. But others are less well recognized. For stomach cancer, a fifth of the risk comes from having too much salt in the diet, data suggests. Some cancers, like mouth and throat cancer, are caused almost entirely by lifestyle choices. But others, like gall bladder cancer(胆囊癌), are largely unrelated to lifestyle.

    Public Health Minister, Anne Milton, said: "By making small changes you can cut your risk of serious health problems- giving up smoking, watching you drink, getting more exercise and keeping an eye on your weight."

    Nowadays, computers and Internets are playing an important part in our life. Some people even say they can't live without them. We usually need to set passwords (密码) when we use computers and Internet. But not all the passwords are safe. In order to keep our accounts (账户)and personal information safe, we must learn how to make safe passwords.

    How can you make your computer and Internet passwords safe? Experts have some advice for you. You'd better remember the advice and they are useful for you. Here are the suggestions.

    Firstly, make your password out of capital(大写) letters. If your password is made of capital letters, it will be difficult for others to get into your account. It only takes a hacker(黑客) 10 minutes to work out a six- letter password made of small letters. But the same password in capital letters takes 10 hours to work out.

    Secondly, add numbers or symbols to your passwords. It may be much safer. Sometimes such password is not easy to remember, but it is really safe.

    Thirdly, never use personal information for passwords and use different passwords for different accounts. Experts say that a user should change his or her passwords every 90 days. In this way, hacker won't guess your passwords.

    Bruce collected the papers Clive collected the cans

    And Mort tied them with string And Dean washed them all clean

    Jason helped Bruce carry the papers Ruby helped Clive carry the cans

    All the way to the recycling(回收) bins All the way to the recycling bins

    When we recycle, we help the plants

    We help the creatures, from eagles to ants

    We help make the world a healthier place

    For one and for all in the human(人类) race