Trees are useful to man in three very important ways. The first important way is that they provide man {#blank#}1{#/blank#} food, wood and other products(产品). Trees provide man and animals with food to live {#blank#}2{#/blank#} the earth. It's not easy {#blank#}3{#/blank#} man to live on the earth without trees.

    The {#blank#}4{#/blank#} important way is that trees give us shade(树荫). On a hot summer day, people can have {#blank#}5{#/blank#}rest under the shade of a tree after they have walked a long way. You can imagine（想象） {#blank#}6{#/blank#} important the shade of a tree is to man and animals.

    The third important {#blank#}7{#/blank#} is that trees help to prevent droughts（干旱）and floods. However, in many parts of the world, man has {#blank#}8{#/blank#} realized the third important way. He has cut {#blank#}9{#/blank#}trees in large numbers.{#blank#}10{#/blank#} the end, he finds that he has lost his best friends.

Dear Jane,

    Thanks for your e-mail. I have ever had the same experience. I even {#blank#}1{#/blank#}（争吵）with my parents. But now, I {#blank#}2{#/blank#}（理解）them. We are growing up, so we don't like {#blank#}3{#/blank#}（依靠）on them, but often, it's hard for our parents to {#blank#}4{#/blank#}（想象）this. To them ,we are still children and they want to help us.

    Sometimes, it's hard for you to talk to your parents. Here's an idea: Write your mother and father a{#blank#}5{#/blank#}（信）. In it, tell your parents what you are thinking about. Then they {#blank#}6{#/blank#} （或许）will understand you better. In your free time, you'd better {#blank#}7{#/blank#}（提供） some help for your parents. For example, you can help your parents do {#blank#}8{#/blank#}（家务活）. You can {#blank#}9{#/blank#} （扫）the floor, take out the{#blank#}10{#/blank#} （垃圾）.In order to get on well with your parents, you must try your best to do everything.

    What's more, you can describe your friends to your parents and tell them more about you and your life.

    I hope this helps!

Jimmy

    In some ways American families are very different from Chinese ones, but in other ways they are the{#blank#}1{#/blank#}. For example, American families enjoy family dinners, support and love each other just as Chinese families do.{#blank#}2{#/blank#} many Chinese students are surprised to learn that American teenagers are allowed to make many{#blank#}3{#/blank#}on their own, and the parents want their children to leave home at eighteen, because they think their children have grown {#blank#}4{#/blank#} This is different from China.

    In most American families, children are encouraged to make their own {#blank#}5{#/blank#}at a young age. They start with small choices and gradually larger ones{#blank#}6{#/blank#}they graduate(毕业) from high school. Parents and family will help{#blank#}7{#/blank#} the choice, but the children themselves make the final decision.

    Americans seldom move back into family homes {#blank#}8{#/blank#}they get older. Instead, they {#blank#}9{#/blank#}to have their own lives. It is important to remember that these are cultural(文化的){#blank#}10{#/blank#}, and that Americans see this as part of the culture.

Do you have a beautiful dream? I know almost everyone 1his/her own dreams. The dreams are very important 2 everyone for they can make people 3 harder.

I am studying in a school now. My dreams is 4 a teacher in Western China. Many children there want to go to school5 they can't. Their families are very poor and the parents don't have enough 6to send their children to school. But going to school and studying is the only 7 to change their life. Teachers are greatly needed there, so I want to be a teacher to help them. I 8 kind to my students and make friends with them. I will give them love and teach 9 how to be a useful person. I think it is a great 10 in the world.

    Mike was the kind of guy you love to hate. He was always happy and always had something interesting to say. If someone asked him how he was doing, he would reply, "Couldn't be better!" He was really a care-free young man and never felt tired.

    Mike used to say, "Each morning I wake up and say to myself, 'Mike, you have two choices (选择) today. You can choose to be happy or you can choose to be upset.' I choose to be happy. Each time something happens, I am always ready to learn a good lesson. I choose to learn from life."

    I tried to understand what he said. Indeed life is all about choices. Every situation is a choice. The bottom line is: You're living your life and you make it either happy or sad.

    Several years later I had a car accident and my legs were seriously injured. When I was lying on the ground, I remembered that I had two choices: I could choose to live or choose to die. I chose to live.

    People like to say, "Choose the one you love and love the one you choose." Why not choose the one we love and live happily?

Astronauts would face dangers both getting to and surviving (生存) on Mars. Let's learn about surviving a trip to Mars.

What would it take to keep people safe and healthy on a trip to Mars? Scientists are already working on it, though the trip may be many years later.

Over the last 60 years, many spaceships have flown by orbited（沿轨道运行）and even landed on the Red Planet. However, machines cannot replace humans. That's why the United States, China and other countries want to send people to Mars. But surviving on this trip would not be easy.

A trip to Mars would be the farthest journey in human(人类) history. Mars is about 225 million kilometers away, so it would take astronauts at least 180 days to reach there. However, it only takes a few days to get to the Moon.

Space travel is dangerous. For one thing, staying in space for long periods makes the human body weak. Also, it puts pressure behind the eyes and causes eye problems. But gravity(重力) machines could help.

Then there's space radiation(辐射) to worry about. It is bad for astronauts when they have long journeys. Scientists are working out the issue. They have found that taking certain vitamins can help.

Astronauts will have to pack light to lift off from the earth. But they won't be able to get the things they need easily. Astronauts on the space station practice for this by growing lettuce and other food in space. Engineers are developing 3D printing techniques（技术）which can allow future Mars astronauts to build what they want.