Every object has weight. But the center of its weight is not always in the middle of the object. If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity is high. But if the bottom is heavier, it won't fall easily. Then we say that its center of gravity is low.
    Look at the first picture. This empty box must fall over, because its center of gravity (C) is not above the line of its bottom (AB).
Now look at the second picture. There is some heavy iron in the bottom of this box. It will not fall, because its center of gravity is above its bottom.

    The computers changed our lives in the 1980s, the Internet changed our lives in the 1990s, and the robots will change our lives in the new century.

    Do you think there will be robots in people's homes? It's not a dream that every home will have a robot.

    Now, robots are not only able to help people do the housework, they can also help the doctors do the difficult operations, play chess with people, play the piano and so on.

    A new cooking robot is used in Beijing. It can cook all the dishes on the menu; you only need to wait two to four minutes. In the future, the robot will be a nurse, a security (安全）guard, or a partner in your life.

    Experts believe robots will be used everywhere from the industrial (工业的） robots to service robots. In the future, robots will become part of the family, and provide close service for people. We all look forward to the new robot age.

    Come and meet the Indian(印度的) elephants and the new tigers from America.  The bears are waiting to meet you, and the monkeys from China are waiting to throw things at you. The lovely dogs from Australia are waiting to laugh at you The giraffes from Zambia(赞比亚) are waiting to look down on you.

Tickets

Opening time

Adults: $2.00 

Children: $1.00  

Under 12: Free 9:00 a.m.-4:00 p.m. (Except(除了) Friday)

10:00 a.m.-3:00 p.m. (Friday)

    Keep the zoo clean!

    Do not touch, give food to or go near the animals.

    E-waste is fast becoming a serious problem around the world. This report will examine this problem and provide some possible ways to solve it.

We live in a society that is producing and using electronics(电子产品) all the time. It is often cheaper to buy new products than to repair old ones. Also, through clever advertising, companies always encourage people to change their old TVs, mobile phones and computers for the latest models. E-waste is created when we throw away old ones. In the EU alone, about 8,700,000 tons of e-waste is produced each year. Sadly, just over 1,000,000 tons is recycled.

    Burying(填埋) e-waste or burning it cause serious problems for the environment. Electronics have dangerous things in them. These things can then get into the ground or pollute the air when they are burnt.

    In recent years,   ▲  . However, their plans are not always managed properly. Sometimes electronics are just sent to poor countries such as Ghana. Here they are often burnt in public areas, which is very bad for people's health. Setting up recycling centers is a good way to solve this problem. E-cycling centers could recycle the parts that can be reused and deal with the rest properly.

    Another way is to make producers responsible(负责任) for their used products. This means that producers must take back old products which are no longer wanted. They should then make sure they are properly recycled or reused.

    As for us, we should try to cut down on e-waste. Change electronics only when we have to. And don't buy a product just to have the latest model.

    E-waste is a serious problem in the modern world. Both producers and users must take actions and try to keep it to the smallest amount.

    Have you ever seen the movie. Big Hero 6 ? Baymax(大白) is a main character in the movie. He's a friendly big robot that looks after people's health. If there is a robot like Baymax in our real life， people will get more benefits. The robot will be especially helpful in caring for the old. The health of old people needs greater monitoring and care.

    Scientists in America are now working to make Baymax a really(实现)- Actually. They have already produced some health care robots. These robots provide brain video games to improve people's memory. The garner can help the old remember things for longer. Besides， these  provide special app (应用程序） to help the old manage their health at home. The apps can check  the old people' heart rate (心率) and tell them to take their medicine on lime. The apps can also record their daily activities. Such collected information helps doctors discover the cause of an illness faster and more correctly. But the health care robots are't as clever as Baymax yet.

    Nowadays，scientists are working on improving the health care robots. They pope the robots can produce electricity by walking across the floor. If they succeed. batteries will not be needed. They also hope the robots communicate with humans in the daily life so to make people happier and healthier.

    Scientists are trying to realize these dreams. Like Baymax， these health care robots may save people's lives in the future. We are looking forward to them.

    Watering plants is an important part of having a garden. But different plants have different needs. Plants like plenty of water, but how do you know what is too much or too little? Here are just a few helpful suggestions you may want to consider.

    3 Do's 3 Don'ts

    Water early.

    Water in the morning before it begins to get hot. It's a perfect time to water your plants. This way they are ready for the hottest parts of the day. Don't water too much.

    Although plants are usually thirsty, too much water can be harmful to their growth. If you notice the leaves are becoming yellow and falling off, it is a clear sign of too much water.

    Drain （排水） properly.

    Be sure to check the surrounding area of your plants regularly. The extra water should be drained well. Don't water late.

    This is especially important. Although not everyone will be able to do their watering in the early morning hours, try not to wait too late in the day. If you water in the afternoon when it is hot, lots of water will evaporate （蒸发）before reaching the roots. If you water in the evening, the roots will be too wet.

    Prevent insects.

    A thin, fine mist （喷雾） will prevent insects from setting on the leaves and flowers. Don't water the leaves.

    The most ideal place to begin is the root. This is where most of the growth and development takes place. In order for your plants to be strong, the roots have to be healthy.

    To really know what works well for your plants, watch them for signs of over watering or signs of not getting enough water. For more great advice on rose watering and growing roses, visit http:// www. my rose guide. com.