Most of the flowers in nature are red, orange and yellow. If we have seen a black flower, it's chance in a million.

    People have made a survey to colors of more than four thousand kinds of flowers and discovered that only eight of them are black.

    As we know, sunlight is formed by seven colored lights. The wavelength of each light is also different, so the quantity(量) of heat in each light is also different. Flowers, especially their petals(花瓣), are easy to be harmed by high temperature.

    Black flowers can take in the light of all the wavelengths that make them dry up because of high temperature, so black flowers can hardly resist(抵抗) sunlight. But red, orange and yellow flowers can protect themselves from sunlight by reflecting(反射) the red light, orange light and yellow light, each of which has a large quantity of heat.

    Our school is a green school．What makes it green？

    First，we have a lot of trees．There are trees in front of and behind every building．Some trees are green only in spring and summer．And some are green all year round．The trees make our school look like a big forest.

    And our school is a green one because we "go green". How do we go green？We have two green days every month．On green days，no students or teachers go to school by car．And we have clean﹣up Day every month．That day，students go to streets to pick up rubbish．Also，we have tree﹣planting Day every spring．We plant young trees on hills．We have three green clubs The members of the clubs look after those trees well．

    Green is not only a colour．It is about life．Please go green with us and make the world a more beautiful place．

    Since the first person walked on the moon in 1969, technology has greatly helped space exploration. In recent years scientists have built a special robot to accompany astronauts on space missions (任务). Because this robot looks and moves like a person, scientists call it a humanoid robot. The latest model of the humanoid robot is known as R2, short for Robonaut 2.

    R2 was first launched into space on February 24, 2011. It was built by the National Aeronautics and Space Administration (NASA) and the car producer General Motors (GM).

    R2 weighs 330 pounds and costs $2.5 million to build. It has arms and a head- filled with vision equipment—but no legs. Its "brain", or computer, is in its stomach. R2's arms can hold 20 pounds. Each bendable finger has 5 pounds of grasping force. R2's hands are also skillful. Since its hands are shaped like human hands, R2 can use human tools to complete tasks traditionally performed by astronauts." Astronauts absolutely have their day packed from the minute they wake up until they go to bed. If Robonaut can provide just an hour's worth of relief to the astronauts doing something they don't want to do, that would make it worth it right there," says Nic Radford, the deputy project manager of R2.

    One advantage of working with R2 will be that ii can't complain about its work! Astronauts will also appreciate the fact that the robot can perform its duties without constant supervision (监管). R2 can be assigned a task and then checked on periodically. If R2 does not complete a task correctly, astronauts will be able to make minor adjustments to adapt (适应) the robot's behavior so that the task gets done right.

    R2 is still in the design stage of development, which means that scientists are frequently testing it and looking for ways to improve it. Right now, humanoid robots do not have the protective equipment needed to work outside the space station. As technology advances, humanoid robots will be able to help astronauts with dangerous tasks as well as routine ones.

    In the future, humanoid robots will be astronauts' eyes in space, going to places considered too difficult or unsafe for astronauts to explore. Some of them will be mounted on wheels to explore the surface of planets or asteroids (小行星). The robots will be able to send back videos and help astronauts gather information about the atmospheres of these places.

    One outcome of using these humanoid robots will be a greater understanding of the interaction between humans and robots. NASA engineers believe that when humans and robots combine forces and work together, the results will be better than what either could achieve alone. John Olson, a director at NASA headquarters in Washington, D.C, says that the project will allow us to go farther and achieve more than we can probably even imagine today.

Face the Stress

    Have you had a headache during a test? Have you ever been so worried about something that you have a headache or even can't sleep at night? If so, then you know what stress is. Stress is what you feel when you are worried about something. {#blank#}1{#/blank#}You may feel angry, sad, scared, or afraid—all of which give you a stomachache or a headache.

    {#blank#}2{#/blank#}Some kinds of stress are beneficial and others are not. Good stress might happen when you're called to answer questions in class or when you have to give a speech. {#blank#}3{#/blank#} For example, you may do a better job in your test if the stress pushes you to prepare better before the test.

    On the other hand, bad stress can happen if the stress lasts too long. You may not feel well if your parents are fighting, if a family member is sick, if you're having problems at school, or if anything else makes you unhappy every day. That kind of stress isn't going to help you. {#blank#}4{#/blank#}

    {#blank#}5{#/blank#} Make sure you keep yourself in mind: Sleep, exercise, leisure, and food. If you get enough sleep and eat healthily, and if you exercise and leave and leave time for fun, you'll probably feel less stressed.