If you are riding a bike in foreign countries, you need to know what these traffic signs mean.

1		This sign means “walk”, you can cross the street along with other people.
2		This sign is the “don't walk” sign. It means you should stop to wait for a while until the sign of “walk” is showing.
3		This sign means that there is a bike lane. If you see such a sign, you must use the bike lane.
4		Car drivers and bike riders must come to a complete stop at “STOP” signs.
5		This sign means you are coming to a zebra crossing. You must slow down to allow people in the zebra crossing to cross the street.
6		This sign means parts of the road are rough. Be careful! Rough roads make you fall off your bike.

    Earth Day is on April 22^nd. People say thanks to the Earth and learn ways to keep the Earth safe and clean. But saying the Earth is not just for grow-ups. Kids are also taking an active part in it.

    The American writer and filmmaker Lynne made a film called Young Voices for the Planet. It lists a lot of stories about different kids who help to keep our environment clean.

Team Marine, US

A group of students an Santa Monica High School started an organization called Team Marine. They tell people why plastic bags are bad for sea animals and environment. In 2011, they successfully made lawmakers(立法者) in their city stop people using plastic bags.

Felix, 15 Germany 

   In 2007, a 9-year-old boy, Felix, started a club. Plant for the Planet. It encourages children around the world to plant trees in their own countries. Felix helped plant 25 million trees in Germany and 120 million trees worldwide.

Alec, 17, US 

    When he was 12, Alec set up Kids VS Global(全球的) Warming. It teaches kid about weather change and ways to stop the world getting warmer and warmer. Alec travels widely to encourage people to help stop global warming. He has given more than 70 talks across the country.   

Olivia, 13, US 

    When Olivia was 11, she heard about the 2010 oil spill(漏油) in gulf of Mexico. She painted 500 pictures of birds to raise money for the clean-up. She raised more than $200,000 to protect(保护) birds and other wild animals.

    Hundreds of years ago, life was harder than it is today. People didn't have modern machines. There was no modern medicine, either.

    Life today has brought new problems. One of the biggest is pollution. Water pollution has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and become angry more easily. Air pollution is the most serious kind of pollution to all living things in the world.

    Cars, planes and factories all pollute our air every day. Sometimes the polluted air is so thick that it is like a quilt (被状物) over a city. This kind of quilt is called smog.

    Many countries are making rules to fight pollution. Factories must now clean their water before it is thrown away, and they mustn't let dirty smoke go into the air.

    We need to do many other things. We can put waste things in the dustbin and do not throw them on the ground. We can go to work by bus with our friends in the same car. If there are fewer people driving, there will be less pollution.

    Rules are not enough. Every person must help to fight pollution.

B

    Surtsey was born in 1963.Scientists saw the birth of this island. It began at 7.30 a.m. on 14th November. A fishing boat was near Iceland. The boat moved under the captain's（船长）feet. He noticed a strange smell. He saw some black smoke. A volcano（火山）was breaking out. Red-hot rocks, fire and smoke were rushing up from the bottom（底部）of the sea. The island grew quickly. It was 10 meters high the next day and 60 meters high on 18th November. Scientists flew there to watch. It was exciting. Smoke and fire were still rushing up. Pieces of red-hot rock were flying into the air and falling into the sea. The sea was boiling and there was a strange light in the sky. Surtsey grew and grew. Then it stopped in June 1967.It was 175 meters high and 2 kilometers long. And life was already coming to Surtsey. Plants grew. Birds came. Some scientists built a house. They want to learn about this young island. A new island is like a new world.

阅读下列短文,从每小题所给的A、B、C、D四个选项中选出一个最佳选项。

    You know how much your telephone has changed over the past 10 years? Your car will change even more than that in the next 10 years.

    One of the biggest changes is that cars will drive themselves. Some day you may not need to drive a car. You will just tell the car where you want to go and it will drive itself.

    Google

    The American company Google has been working on a self-driving automobile for years. These cars are already on the roads in the United States, mainly in California.

    Google cars are truly self-driving. These cars have no steering wheels(方向盘) or pedals(刹车踏板).

    Last week, police ordered one of Google's cars to stop for driving too slowly on a public road. The car was not against any law, so no one was punished. But police did speak to the operators of the vehicle(车辆).

    According to Google, its self-driving cars have been driven nearly 2 million kilometers. That is equal to the distance the average person drives in 90 years.

    So far, no Google self-driving car has gotten a traffic ticket. Some of them have been in accidents when other cars hit them.

    Tesla

    Another American company, Tesla, added an “Autopilot(自动驾驶仪)” feature to its cars last month. Tesla put the feature, a computer software program, in cars that were built after September 2014.

    With the Autopilot turned on, the vehicle drives itself. The car will speed up, slow down, brake and steer by itself.

    You can take over driving any time by turning the steering wheel or touching a pedal. Your car will slow down if the vehicle in front of you gets closer. It will turn at bends and change lanes if you use the turn signal.

    Tesla Autopilot takes over driving at speeds over 29 kilometers per hour when you press a button twice. Autopilot is made for cross-country driving. It keeps you in the lane and helps you avoid hitting other cars.

    Other Self-Driving Cars and Buses

    Other companies such as Mercedes-Benz, Audi, BMW, Volvo and Toyota are working on self-driving cars. Another company called BestMile is also working on self-driving buses in Switzerland. The buses can hold up to nine people and will be tested for two years.