The earth is about 4,600 million years old. Modern man has lived on the earth for only 35,000 years, but during that time, we have changed our planet in many ways. Many of the things that we have done are good, but more are not good for the earth.

    Water pollution

    A lot of people, birds and fish die each day because of water pollution. Factories have polluted the land and the water. As a result, many river and lakes are now dead.

    Air pollution

    In big cities, factories, as well as cars, trucks and buses are the biggest cause of air pollution. Many people in cities now have bad health problems. For example, Mexico city used to be a beautiful sunny capital, but today it is almost covered by thick brown clouds.

    Soil pollution

    In order to have a good harvest, most of the farmers use chemicals too much on their fields. That's bad for the soil. But this kind of pollution is difficult to stop.

    Hope for the future

    These problems are very serious for our future, so all of us should do something to improve our environment. If we can stop pollution, our planet will become more and more beautiful and our health will be better. Let's be greener people.

    The World Health Organization(世界卫生组织) says air pollution kills seven million people around the world each year. Even if polluted air does not kill us, it can make us very sick.

    However, breathing dirty air may do more than hurt your body. It can also affect(影响) your brain and your ability to think.

A new study shows that air pollution can cause a "huge" reduction(减少)in our intelligence(智商).The researchers reported that long-term exposure(暴露) to air pollution can affect a person's mental(智力的) abilities in two areas: language and math.

Xi Chen, the researcher of the Yale School of Public Health led the study. He and his team found that breathing polluted air can reduce a person's education level by about one year.

    Chen said that the effect(结果) generally is worse for those over 64 years of age, for men and for those with little or no education.

    "The older persons-they are more affected. And we find, quite interestingly, men are more affected than women. And people working outdoors are more affected than people working indoors.

The researchers noted that the effect of pollution on language ability is even more serious as people age, especially among men and the less educated.

    Why were language skills more affected than math? There are two main kinds of tissue(组织)in the brain: white matter and grey matter. White matter is more connected with a person's language skills, while grey matter is connected to our ability to solve math problems. Studies have shown that air pollution has a great effect on the white matter in the brain, but not the grey matter.

    Chen said that air pollution did affect the math skills, just not as much as their language skills.

    The world's first hydrogen-powered(氢动力) trains have begun running in Germany last month. The new trains will run 100-kilometer trips and can travel up to 140 kilometers an hour.

    A French railroad company called Alstom built two hydrogen-powered trains. Teams in Germany and France cooperated on the project, which was supported by the German government. The new train model, called the Coradia iLint, signals the beginning of efforts in Germany and other nations to move away from pollution-producing diesel(柴油) trains.

    Compared(与…相比较) with diesel trains, the Coradia iLint is designed to run on non-electrified train lines with low levels of noise. It uses a process that combines hydrogen and oxygen to produce electrical power. If the system produces more energy than the train needs at that time, it can store the extra energy in batteries. The only emissions(排放物)are water and steam.

    A single tank of hydrogen can run a Coradia iLint train for about 1,000 kilometers. This is very similar to the distance a diesel-powered train can run on with a single tank.

    Hydrogen-powered trains cost more than diesel trains to build. But Alstom officials say the operating costs are much lower. The company plans to provide another 14 Coradia iLint trains by the year 2021. Several other European countries have also expressed interest in developing hydrogen train systems. France has already said it wants its first hydrogen train to be operated by 2022.

    Technology is everywhere. In fact, almost all of us carry a certain piece of technology with us every time we leave the house. What I always forget, though, is just how useful and powerful technology can be when we want to help others.

    There is not a single room in my house that does not have some electronic devices(设备).Whenever I am at home, I am almost always using at least one electronic device. If you walk into my living room on any given day, you will find that, first, I have the television on. At the same time, I usually have my laptop resting on my knee, or I am using my mobile phone. Even when I'm not at home, I am always using my phone, and at work or in cafes, I sit down and connect to the local wireless network on my laptop.

    I must say that I waste a lot of time on the computer and the time I spend on it could be much better spent if I were to take up a little online volunteering.

    Recently I discovered just how much online volunteering there is to do in the world. From using your language skills to do translations, to developing and managing projects and helping with IT work, there is so much that so many people can do to help people in their own countries and across the world. The United Nations, in fact, has a huge page with "Volunteers Recruited" on its website.

    This work can support the poor and help charities who cannot pay for staff members. Many organizations only require you to work an hour a week, some even less. And the support provided by online volunteers can really help make a difference to those in need.