If you put your history notes under your pillow (枕头) and sleep on them the night before an exam, will you do any better on the test? Most of us have hoped this might help. However, _______ can't go through the pillow into your brain. But that doesn't mean you can't learn while you sleep.  

    Scientists aren't exactly sure how it works, but they have discovered that the brain can learn things during sleeping hours.

    In one experiment(实验), researchers gave German speakers some Dutch words to learn. Then, they divided them into three groups. The researchers played Dutch words for people in Group 1 while they slept, without telling these German speakers what they were doing. The sound was low so it didn't wake them up, and only the newly introduced words were used.

    Another group listened to the same words while they were awake. The researchers found the people in Group 1 were better able to identify(确认) and translate the words later. This was true only for the words that were played while they slept. The third group listened to words while they walked. The walkers did not have the same success remembering the words as the sleeping group.

    The researchers later found that people had more slow-wave(慢波的) brain activity throughout the night. They said that more slow waves made people have better memory for the new words.

    In most parts of the world, many students help their schools make less pollution. They join environment club. In an environment club, people work together to make our environment clean.

    Here are some things students often do.

    No-garbage lunches. How many lunch bags do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classa that make the least garbage and report them to the whole school.

    No-car day. On a no-car day, nobody comes to school in a car including the students and the teachers. Cars give pollution to us, so remember:

    Walk, jump, bike, or run!

    Use your legs! It's lots of fun!

    Turn off the water! Do you know that some toilets can waste twenty to forty cubic（立方米）of water an hour? In a year, that would fill in a small river. In the environment clubs, students mend（修理）those broken toilets.

    We love our environment. Let's work together to make it better.

    What do you see when you look at abstract (抽象的)art? Can you understand it? Does it look like anything?

    Abstract art became popular in the early 20th century. Artists did not want to paint, draw, or sculpt things exactly like they looked. They didn't want their art to be realistic(现实的). They were more interested in basic shapes and colours.

    Picasso is probably the most famous of these artists. He painted and drew in many, many styles. Sometimes he used a lot of blue colours (his "blue period"). Later, he used more red and pink colours (his "rose period"). Many of his other paintings are called "cubist (立体派的)" because they are made of painted squares.

    After a long time, Picasso's paintings became more and more abstract. He painted people and things using strange shapes. His work was so strange that many of his workmates didn't understand it.

    Kandinsky, another famous artist, used lines, shapes, and patterns to paint his subjects. His paintings also used strong colours to express feelings. Other artists like the surrealists (超现实主义画家)，were interested in subconsciousness (潜意识). Painters like Breton and Magritte used many symbols in their work. The meaning or subject of their work wasn't always clear. Dali, another surrealist artist, painted pictures that looked like dreams.

    There are still many abstract artists around the world. That's the way many artists prefer. They want each person to look at art and find their own meaning in it.