Are you a happy person most of the time? Or do you easily get angry sometimes? Everyone has a different temperament (脾气). It is usually believed that both genes (基因) and environment may affect people's temperaments in different ways. But now scientists have found that the season of birth also plays a role.

 Scientists from Budapest, Hungary, studied 400 university students. In the study, the students needed to finish a questionnaire (问卷). The purpose of it was to find out which of four kinds of temperaments they most had. From the questionnaire, scientists found that the students always answered something like "My mood often changes for no reason" and "I love to deal with new projects, even if it is risky". These answers were then matched with their birthdays.

  They discovered that people born in summer easily change between sad and happy moods compared to people born in winter. Those who always feel positive are mostly born in spring and summer.

The study also found that those born in autumn less probably had a mood of depression which may easily drive them to cry, while those born in winter were not easier to be angry.

 Scientists said that this was probably because the seasons had an influence on certain chemicals in the human body. And the chemicals are important to control people's moods even in adult life.

  ____________________________________________________________________________

"It seems that when you are born may increase or decrease your chance of developing certain mood disorders (紊乱)," lead scientist Xenia Gonda told The Telegraph.

E

Recently, China announced it had achieved success in drilling fire ice or methane hydrate (天然气水合物，即可燃冰), from the seabed in the Shenhu area of the South China Sea. It produces high amount of energy when it is burned, leaving nothing but dioxide and water.     Many countries, including the United States and Japan, have long beeaban doing research on methane hydrate, but taking it from bottom of the sea has been a common problem they are facing. According to reports, China succeeded in drilling methane hydrate for a number of days continuously and got an average of over 16,000 m3 daily. It is believed to be a big breakthrough.

Scientists say there is about 21, 000 trillion (万亿) m3 of methane hydrate in the world. If we can use it, it can meet the world's energy need for 1, 000 years. However, it is too early to say a new energy source (来源) has been found because we are still facing two main challenges—environmental risk and economic (经济的)cost. When methane hydrate is taken from the seabed, it may go into the air easily. That's very bad for the environment because methane is one of the worst greenhouse gases. Besides, drilling methane hydrate is very expensive as well.     However, China's technology breakthrough is very important because it shows the way researchers across the world should take. It also raises hopes that one day we can drill methane hydrate as a source of energy.

C

    Paul is a photographer(摄影师). He went to the Arctic to take pictures for NationalGeographic(《国家地理》). Finally, he saw a big and white polar bear swimming to him in the icy water.

    Paul lay down the ice to get a better photo, but the polar bear jumped out of the water and tried to attack him! Luckily for Paul, the ice cracked(破裂), or broke and the bear fell back into the water. The polar bear wasn't so lucky. It couldn't get a meal and had to swim farther away to find food.

    To understand the polar bear's problem, you need to know two things about the Arctic. First, the Arctic is mostly ocean(海洋). Second, ice covers(覆盖) a lot of the Arctic Ocean. In winter, the ice is thick, but in summer, the ice becomes thinner and breaks into pieces. Sea ice is the key to survival for Arctic animals. However, because of global warming, Arctic temperatures are rising and polar ice is melting(融化).

    Polar bears need ice  to hunt(捕捉) seals, their favourite meal. They stand on the ice and wait for the seals to come up for air. As Arctic ice melts, polar bears have to swim farther to find ice floes, or large pieces of floating ice. Sometimes, bears have to swim more than 200 km to find an ice floe. Some bears cannot swim that far and sadly they drown(淹死).

    On his last trip, Paul saw three dead bodies of polar bears. Before global warming threatened(威胁) Arctic ice, a dead bear was a rare sight. Paul is sad to see the dead bodies. Wildlife experts(专家) think global warming will have a terrible effect(影响) on polar bears. In the future, polar ice will continue to shrink and endanger the bears. Some scientists believe 65 percent of the world's polar bears will disappear(消失) by 2050. In other words, polar bears are in great danger.

    What will the world be like if cars can drive themselves? Imagine seeing an empty car passing by on its way to pick up its owner or a car full of passengers who are reading, listening to music or even sleeping. The passengers in the car needn't worry about the road ahead.

    Well, all of this could be the future of driving. There are several companies, including Google, Tesla, Mercedes-Bens, Audi, BMW, Volvo and Toyota, working on driverless cars. They are now in the testing stages (阶段). If the tests are successful, these self-driving cars could be available very soon. But how is it possible for a car to drive itself?

    Modern cars are able to take the place of drivers during certain situations. For example, they can park themselves or slow down when they detect (发现) objects nearby. They can also control the speed if there are dangerous condi-tions, such as snowy roads. Scientists and engineers believe that, with the help of wireless signals (无线),cameras and GPS, creating a safe self-driving car might be possible in ten to twenty years.

    Self-driving cars may help cut down the number of serious accidents caused by careless drivers or dangerous condi-tions. However, there are still some people who do not like the idea. American lawyer, White Drake, for example, doesn't believe these cars are safe. He thinks the possibility of the technology making a mistake will be too high.

    Every year on April 22, People all over the world celebrate Earth Day. It is a time to work to keep our earth clean. People plan projects to clean up the land, air and water.

    U.S. Senator Gaylord Nelson first thought of the idea for Earth Day in 1962 when he saw polluted rivers and cities with smoke. He needed to get support from Americans to clean up the earth. Finally, on April 22, 1970, 20 million Americans celebrated the first Earth Day! Now many countries around the world celebrate it, and you can, too.

    How can you celebrate Earth Day? Here are a few ideas:

    Join a clean-up project-Clean up your street or a favorite beach.

    Save energy-Turn off the lights when you leave a room, and use public transportation.

    Use less water.

    Reduce(减少)/ Reuse/ Recycle ― Practice the three Rs: First, reduce how much you use. Then reuse or recycle what you can.

    You can make a difference on Earth Day and every day!