Scientists think that there has been life for__31_ of years. However we haven’t found life on other planets _32_ . The earth is a planet and it _33__ around the sun. Seven other planets also go _34_ the sun. The sun and its planets are __35  the solar system. The solar system is a small part of our galaxy.
Scientists __36_ lots of spacecraft to look at other planets in the solar system, and some spacecraft have gone __37_ the solar system. However, no one __38_ any life in space yet.
But why has no one from other planets sent us a message ? Have they tried to send _39_ to us ? _40_so many stars in the universe, are we alone, or is there life out there in space ? We don’t know.

Passage 5
Here in Siberia (西伯利亚), the winter is always very long and it’s very, very cold! It starts to snow in November and the snow won’t leave until May. The temperature is usually about -25℃, but it’s sometimes much colder. When it’s -35℃, children can’t go to school, but grown-ups still go to work! We wear a lot of warm clothes: socks and boots, sweaters and fur coats. All the houses have heating, so it’s never cold inside. In winter, we close the windows to stop the wind from getting in, and we don’t open them again until spring.
In spring and summer it rains a lot, and we don’t often see the sun. In summer it’s often about 25℃, but the weather is very changeable. One day it’s 25℃, and the next day it’s 10℃. People say that the weather was even colder in the past.
【小题1】How long is Siberia’s snowy time?
【小题2】What are used in Siberia to keep the people and houses warm?
【小题3】Do children go to school when it’s -35℃ in winter?
【小题4】What’s the weather like in spring?
【小题5】How does the weather in Siberia often change in summer?

Why are you always tired, do you know?
First, if(如果) we can’t   31  well, we will(将) be tired. But we are often too   32  . We can’t finish our work in the day  33   we have to do it at night. We go to bed   34  and we get up early in the morning for school or work. Most people need at least(至少) eight   35   or some more. If we sleep for only five or six hours a night, we will be tired.
Second, when we are ill, we will be tired. But we don’t know we are ill. So if you are always tired, maybe you are not so    36  . You’d better go to see a    37  .
Third, maybe you eat    38   food, like hamburgers, meat, chocolate or coffee. If you are ill and tired after eating some food, please don’t eat it    39   to see if you are well. 
At last, if the air around you isn’t nice and clean, you will feel tired. So please open your windows often or go out for a walk and you will feel    40   .

I was tired and hungry after a long day of work. When I walked into the living-room, my 12-year-old son looked up at me and said, “I  31  you.” I did not know  32  to say, and I just stood there, looking  33 at him. My first thought was that he must need help with his homework. Then I asked, “What was that all about ?” “Nothing,” he said, “My teacher said we should tell our parents we love them and see what they say.”
The next day I called his teacher to  34  more about what my son said and how the other parents had reacted﹡. “Most of the fathers had the  35  response﹡ as you did,” the teacher said, ”When I first suggested ﹡that we try this, I asked the children what they thought their parents would say. Some of them thought their parents would be surprised.”
Then the teacher explained , “ I want my students to know that feeling love is an important part of  36  . I’m trying to tell them it’s too bad that we don’t express﹡ our feelings. A boy  37 tell his parents he loves them.” The teacher understands that sometimes it is  38  for some of us to say something .
That evening when my son came to me, I took him in my arms and held on for a while, saying, “Hey, I love you,  39  .” I don’t know if saying that made either of us healthier,   40   I did feel pretty good.