You probably know many of the things that you can do with the hundreds of different muscles in your body. But have you ever thought about how the muscles in an animal's body are different from yours? An animal's muscles are made to do the things that are most important for its life.

    Lions are hunters. They depend on their ability to catch other animals. Lions must be fast in order to catch their prey(猎物). The powerful muscles in their back legs allow them to run at speeds of more than 30 miles per hour. They can also jump a distance of more than 35 feet. The strong muscles in their front legs help them catch their prey.

    Snakes also use their muscles for hunting prey and for movement, but their muscles work in very different ways than lions' do. Because snakes do not have any legs, they use their muscles to push against the ground or other objects to move themselves forward. Their muscles also allow them to eat things that seem much too large. For example, a snake may eat an egg that is larger than the width of its body. How does this happen? The snake's strong neck muscles work together to push the egg down the mouth.

    The elephant's long nose has a lot of muscles. Scientists believe that the nose alone has more than 100,000 muscles! This is because the elephant uses its nose much in the same way that people use their hands and fingers. Even though the nose is large, it can perform surprisingly tasks. For example, an elephant can pick up a small leaf from the ground. The nose can also be a powerful tool. An elephant can use its nose to pick up a tree by its roots or even to lift a baby elephant.

    The great muscles of these animals seem pretty unbelievable. But the muscles in your body work exactly the way you need them to. After all, it might be fun to be able to jump a distance of 30 feet, but as a human being, there is just not much need for it.

    All living things on the earth need other living things to live. Nothing lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another, one eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain (食物链). Some food chains are simple, while others are not. But all food chains begin with the sun, and all food chains become broken up if one of the links (联系) disappears.

    All life needs sunlight to live on. But only plants can use sunlight directly (直接). Plants are “factories”. They make food from sunlight, water and things in the soil (土壤) and air.

    Plants feed all other living things. Animals can only use the sun's energy (能量) after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly.

    What about human beings? We are members of many food chains. We eat wheat (小麦), rice, vegetables, fruits and so on. We also eat meat and drink milk. But humans often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them cannot be eaten. If men eat the fish, they will get strange diseases (疾病).

    Each form of life is linked to all others. Breaking the links puts all life in danger.

    Do you know when Earth Day is? It is on April 22nd, and it began in the US in 1970. Earth Day in our country began in the 1990s. Earth Day is a good time for people to think about what they can do to make the Earth clean and beautiful, because now the environment on Earth is getting worse and worse. In fact, there are many things we can do to protect our Earth.

    Plant trees.

    Planting more trees helps to reduce greenhouse gases (温室气体), stop the earth from running away and provide homes for animals.

    Don't waste.

    Do not waste water. Use both sides of paper when you write. Turn off the light when you leave. Take your cup with you. Take your own shopping bags to the supermarket. Stop using the plastic bags. Don't use any disposable things. We should save energy.

    Don't throw rubbish in the streets.

    When rainwater washes over the rubbish, it becomes polluted. The polluted water flows into the rivers and seas.

    Ride your bike or take a bus.

    Too many cars pollute the air and waste energy.

    Remember: Every day is Earth Day.

    We should protect the Earth every day, not just on Earth Day. The Earth is our home. Let's do our best to make the Earth cleaner and more beautiful.

Parents are the ones who love you most on the earth, However, you don't often thank them. Sometimes when you want to, it's too late. {#blank#}1{#/blank#}

{#blank#}2{#/blank#}. " You may be busy, but don't forget to call your parents and tell them bow much you miss them. 

"I love you. ". {#blank#}3{#/blank#}, You can't give back everything they've done for you, but this small act will make them feel warm. 

I'm sorry. " You may hurt them before but they still love you. You may try to go back in time and make everything right. {#blank#}4{#/blank#}

Thank you for making me what l am today. " You can never thank them enough for this. {#blank#}5{#/blank#}Let them know they are the real heroes in your life. 
 

 For as long as humans have appeared, we have been the smartest species(物种) on Earth. Monkeys know how to use simple tools. Elephants can be taught how to count. But things like art, literature, the Internet, and space travel have only been made possible by the amazing intelligence(智力) of humans. And yet, there are some who believe that we can create machines that can think and feel just like we do. Artificial intelligence, or AI, is defined (定义) by Merriam - Webster as"the ability of a machine to copy intelligent human behaviour".

AI is around us every day. From Apple's voice-activated assistant Siri to the software algorithms(算法) that shipping companies use to deal with deliveries,AI is very much a part of our lives.

 But why do we try hard to create machines that can think the way we do? AI can make our lives much easier. Imagine being able to be in a car, tell it the place and sit back in comfort as the AI - guided self- driving car takes you there. We' re already getting there—— Changsha became the first city in China to roll out self - driving taxis in April 

2020. Moreover, AI can control lighting, temperature, and security systems, making homes more comfortable and energy - saving.

 However, there are risks (风险) . What if we somehow produced an artificial intelligence that was smarter than us? Would they control us? Would they take away our jobs? These are difficult questions that AI researchers ask themselves all the time.

 Except for the risks, it has been already clear that Al is here to stay. Only time will tell if it will lead us into a new age of prosperity(繁荣) , or be our end.