Don't be too surprised if you see a car going down the road without a driver in Beijing these days. {#blank#}1{#/blank#}Last month, Baidu began to test its self-driving cars on open roads in Beijing.

    {#blank#}2{#/blank#}Since then, companies like Tesla, Uber and Baidu have been working to produce and test their own self—driving cars.

    Self-driving cars are safer than regular cars. {#blank#}3{#/blank#}They can remove the stress of driving and allow disabled or blind people to get around more easily.

    {#blank#}4{#/blank#}In one test, researchers pointed a laser pointer (激光棒) at the car's sensors (传感器) while it was moving. The car mistakenly thought that the laser beam was in its way and slowed down or changed the direction.

    The software that is used to direct the cars may not be safe enough. {#blank#}5{#/blank#}When we use our computers or smartphones, they sometimes crash (崩溃) without any reason. But if this happened to a self-driving car, the result could be deadly. Improvements to the software could be a solution to this problem.

There are many colors in nature. But do you think that a color has weight? Let's do a test.

First, put two objects with the {#blank#}1{#/blank#} weight into two boxes. Then cover the boxes. Third, wrap (包裹) one box with a red piece of paper, the other with white. Now hold the boxes {#blank#}2{#/blank#} your hand one by one. Which one is {#blank#}3{#/blank#} ? It is certain that you will think the red one is heavier. Why do you think so? A scientist did many {#blank#}4{#/blank#} and found that different colors have different weights in a man's mind.

Also, scientists say that people accept the colors they like, and {#blank#}5{#/blank#} the colors they hate. So your body and mind will be {#blank#}6{#/blank#} by using the colors you like. Or you'll be nervous {#blank#}7{#/blank#} even get ill. For example, you {#blank#}8{#/blank#} blue and hate red. If you stay in a room with red windows and wallpaper for two hours, you'll feel you have been there for {#blank#}9{#/blank#} hours. But if the room is blue, you'll feel you have been there for only an hour, And, if a person walks {#blank#}10{#/blank#} of a blue room and into a red room, his temperature will rise. That means our body temperature will change with different colors.

A: What's the matter, young man?

B: {#blank#}1{#/blank#} And I hardly ever sleep well.

A: That sounds bad. Let me have a look.

B: Do I have a fever, doctor?

A: No, your temperature is all right. {#blank#}2{#/blank#}

B: Oh, I usually play computer games until very late.

A: {#blank#}3{#/blank#}

B: No. I want to sleep more in the morning. Can you give me some medicine?

A: Sorry, medicine can't help you. {#blank#}4{#/blank#} First, stop playing too late at night. Second, take much exercise every day. Third, eat healthily. Then you will feel better soon.

B: Thanks a lot, doctor. {#blank#}5{#/blank#}

Buying second-hand things is becoming more popular these days. People sell all kinds of second-hand things, such as clothing, books and electronic products (电子产品) online every day.

Some people have bought more things than they really need, according to a speech given by the founder of a second-hand book-trading app (应用程序). As many people like a simple lifestyle, they are selling their used things cheaply. Shoppers choose them because of the low price. What's more, they think using second-hand things is good for the environment.

Chen Junjun, a student in Shanghai, often uses the app to look for the books she wants, just like on other shopping websites. The difference is that the books on the app are much cheaper—as much as 70% cheaper than new books.

It's reported that lots of people like Chen often buy second-hand books. The app has over 3 million users and sells about 20,000 second-hand books every day.

Buying second-hand books can even connect (把……联系起来) readers. Zhao Kaiqi, a student in Harbin, once found a note in a second-hand book she bought. "Its previous owner shared her ideas on the note. It was so heart-warming," Zhao said. "I want to do the same thing in the future."

Scientists have found out that wearing different colours can have different power. If we are sad,we choose to wear some dark colours. If we are happy,we often wear some bright colours. So how can colours change our feelings? What colour should we wear? Here is some advice.

If you are feeling sad,don't wear black. It will make you feel worse. But if you choose green or red,it will make you feel better. Red can make you have more energy. Blue can make you think better and get good ideas. Orange can make you happier. You can be cleverer than before if you are in yellow. So yellow is good for your studying. It is easier for you to find your love when you are in pink. When you see someone wearing black,you can feel safer.

So try to make you happy by changing the colour of your clothes.

Heath is important to everyone. 1 should we do to keep healthy?

One important rule is to exercise often. The Fangs try to exercise every day. Mr Fang is2 geography teacher. Because he must3 to work before seven o'clock, he can't exercise in the morning. But he runs every evening. He walks a lot, too. He walks to school every day, and after school he plays different sports4 his friends or students. Mrs Fang goes to a swimming class once a week. 

5 it isn't always this way. Last year Mr and Mrs Fang6 everywhere in their car, even to the small store near7 house. They thought they had to use the car all the time. They seldom walked. Then they became fatter and fatter and got stick8 , so they wanted to have a change. They believed they shouldn't be lazy any more. Now, they feel much9 .

We needn't exercise every day, but we should try our best10 as often as possible.