Our sun is a star, and nine worlds (天体) move round it. Worlds like these are planets. But here are other stars, other suns, not only thousands of them, but millions of them. Do different stars have planets? We can see the planets round our own sun. But we haven't been anymore. The stars are too far away from us. Stars give out light, but the planets don't have any light of their own. So we can't see them. They are too far, and too dark. Still, we can tell that some stars have planets. While a big planet goes round, it pulls its star to one side. And sometimes we can see this. Then we know that the star has a planet. For example, Barnard's Star is a small red star. And it is the quickest star in the universe. But sometimes it moves slower, and then quicker again. We have known Bernard''s Star for many years, and now we are sure it has a planet.

    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.

    What is a museum? A museum is a good place to keep old and beautiful things. A museum may be a place to learn about science and a place to find out about art or people or animals.

    What is inside a museum? Some museums have old cars and airplanes. Many museums have pictures and statues(雕塑). Others have rocks and old bones (骨头). One museum even has a real old street inside. It has shops and people's statues doing business. It looks so real that one might feel that he was back to the old time.

    Many cities have museums. Some very small towns have museums, too. Indianapolis has a children's museum. Children do not have to pay (付款) to get in. Children often go to the museum. They like to look at the dinosaur (恐龙)bones. They see a white bear ten feet tall.

    On Saturdays, Indianapolis children can hear talks about animals and trees. They see movies. They take hikes. They even learn to make things there.

    Around the world, there are about 7,000 National Parks. Most of them cover huge areas of land where nobody lives. However, the National Parks in England include places where people live and work, as well as wild areas where there are few human activities.

    The National Parks in England are called "England's Breathing Spaces" because they are places where people can go to be in the open air, away from the dirt and noise of cities. They provide wonderful scenes of mountains, woods, grasslands and wetlands. And there are plenty of activities to do in all of the National Parks in England. Visitors can walk or ride bikes for fun. Many of the parks put on activities for families.

    Every year there are about 110 million visitors to the parks, bringing many benefits(益处) to the areas. At the same time, it creates problems, too.

    First, life can be difficult for local people. Car parks and roads are too crowded. Gift shops and cafes take the place of many everyday shops. Even house prices in some areas can become too high. Besides, country roads can be damaged, for too many people walk, cycle or ride horses on them. Roads can be rebuilt, but then they look less natural. Another big problem to the National Parks is litter. In the parks it is a danger to wild animals. Broken glass can also cause fires by focusing the rays of the sun. Such fires in wild places can be out of control.

    _______All National Parks in England are making more rules, which tell people how to take good care of their environment. If these rules are followed, the National Parks will be well kept and continue to give pleasure to many people for a very long time.

    We have to be fit, no matter (不管) what age we are. It's very important for kids. That's w{#blank#}1{#/blank#} they have P.E. class.

    In Britain students have two hours of P.E. each week. P.E. includes sit-ups, press-ups (俯卧撑) and skipping rope.

    Students also p{#blank#}2{#/blank#}football, basketball and cross-country running. In summer kids run and do the high and long jumps.

    When I was at school my favourite was trampoline(蹦床). Jumping high into the air always made me excited. But you need to be c{#blank#}3{#/blank#}. Sometimes you don't land where you planned!

    When you get your report card there will be a grade for P.E.. Your parents will see how good you are a{#blank#}4{#/blank#} push-ups, as well as maths. But the grade for P.E. doesn't affect (影响) your chances of g{#blank#}5{#/blank#} into a good school.

阅读下列短文, 从下面每个小题的A、B、C、D四个选项中选出最佳选项。

A study conducted by the University of Leeds in the United Kingdom suggest that watching cute animals may lead to a reduction in stress and anxiety.

The study examined how watching images and videos of cute animals for 30 minutes affects blood pressure, heart rate(心率) and anxiety. In December 2019, 19 people, including 15 students, joined in the study.

"There were some kittens, there was puppies, there were baby gorillas, there were quokkas —cute creatures found in Western Australia, are often referred to as 'the world's most cheerful animals'." Dr. Andrea Utley, a professor at the University of Leeds told CNN. The study was timed during winter exams, a time when stress is at an especially high level for students, according to Utley.

 The study recorded that the average blood pressure dropped from 136/88 to 115/71, which the study pointed out is "within ideal blood pressure range." Average(平均的) heart rates were lowered to 67.4 bpm, a reduction of 6.5%. Anxiety rates also went down by 35%.

"I was quite pleasantly surprised that during the session, every single measure for every single participant dropped some — heart rate reduced, blood pressure reduced," Utley said. "When they left, they filled the questionnaire(调查问卷) in again and showed that they were feeling less worried."

When questioning the participants, the study found that most preferred video clips over still images, particularly of animals interacting with humans.