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    No Car Day was first started by 34 cities in France on September 22, 1998. It was started to protect the environment. By now, more than 1,000 cities around the world have had a No Car Day.

    The first No Car Day in China was in Chengdu in 2001. Other cities including Taipei, Shanghai and Wuhan, also support the day.

    In Beijing, more and more people are taking part in the activity. It asks drivers to leave their cars at home for one day each month and walk or ride a bike to work. It also calls on Beijingers not to use cars on June 5th (World Environment Day). The slogan for the day is, "If we drive for one less day, we can have one more nice day."

    So far, more than 200,000 drivers have shown their support. "We can't control the weather, but we can choose not to drive," said Wu Zhonghua, a car club chairman. Beijing is trying to have 238 blue sky days this year. In the first quarter of 2007, Beijing only had 52 blue sky days. This was 11 days less than the number for the same period last year. Much of the dust comes from the desert, but cars cause most of the air pollution. We must do more for No Car Day.

    With the development of the technology, 3D printing is becoming more and more popular. We are now able to print things such as clothing, musical instruments and even cars. People and businesses are able to create the things they need very quickly and easily by using 3D printers.

    But can you imagine printing food? Some scientists are trying a new way to get the dining experience by doing this. They hope that having a 3D printer in the kitchen will become as common as the oven or blender. Scientists say that they are easy to use: you simply have to choose a recipe (食谱) and put the uncooked "food ink" into a printer. You can also change the instructions to make the food you want. This means that it would be very quick and easy to create tasty and rich meals.

    Using 3D printers to create your meals would also be saving the environment. There would be less need for traditional growing, shipping and packaging processes as food products would be a lot quicker and better. For example, tree leaves and insects could be turned into tasty products! Printing food could also help people who have a swallowing (吞咽) trouble. They could program the printer to print softer kinds of foods so that they would not have difficulty swallowing them.

            It could take away many jobs, including those for growing, shipping and packaging food. Imagine a world where there was no need for growing or producing and the same tastes could be printed from an uncooked "food ink". Besides, traditional restaurants might lose business. Also, we have to consider: is it really possible to get everything we need from them?

    As we know, cooking and eating together with family and friends has long been a traditional and enjoyable activity. It is hard to imagine a world where the pastime of cooking is dead and meals can be created at the touch of a machine.

    I'm sure you all know how important recycling is. Recycling is when you take old things and turn them into new things. It sounds like magic. But it's actually very scientific.

    Have you ever had trouble sleeping in a new place? Lots of people do. And now researchers from Brown University in Rhode Island think they know why. They found that one-half of the brain "remains more awake" than the other half when people are trying to sleep in a new place.

    The sleep findings were reported in Current Biology by Brown University. In their report, the researchers said many people report that they have a harder time sleeping the first night at a hotel or other places outside their home. They call it "first-night influence". "In Japan they say, 'If you change your bed, you can't sleep,'" said Yuka Sasaki, one of the report's writers. "You don't sleep very well in a new place. We all know about it."

    The researchers measured brain waves (测量脑波) for 35 volunteers over two nights in a laboratory. The two nights were a week apart(间隔).They found during the first night the left half of the brain was more active than the right half. This was during the first deep-sleep period, the researchers said.

    Sasaki said a lot of questions remain.

    Researchers did not keep measuring brain waves all night long. So, they don't know if the left half keeps "watch" all night, or whether it" works in shifts (轮换) with the right half later in the night" .They also do not know why the brain activity, at least during the first period of deep sleep, is always on the left half.

    For some, this research may be calming. It is good to know that our brain is "looking out for us" in a new place. But it may not help with sleep. That brain activity, at least according to this new research, makes it harder to get the sleep people need to wake up well rested in the morning.