What is the most popular fast food today? Potato chips? Hamburgers? Or Sandwiches?Walk into almost any supermarket or corner store in America and you will see potato chips．Americans are the biggest eaters of potato chips and people in many other parts of the world enjoy them too．Do you know where this very popular fast food comes from?

    One day, almost 150 years ago, a cook in an expensive restaurant in New York State was preparing popular food—French fries．A customer in the restaurant didn't like the French fries, and complained(抱怨)because they were too thick．The cook cut some potatoes into thinner pieces and fried them．The waiter brought them to the customer．The customer tasted them, and asked to see the cook because he was still not satisfied ．

    The cook went to speak to the customer．The customer complained loudly about the chips again．The cook became very angry because the customer was so rude．He decided to play a trick(戏弄)on the customer．He cut some potatoes so thin that the customer wouldn't be able to pick them up．To the cook's surprise, the customer loved the new chips, and soon other customers wanted them too．People went home to tell their friends about this new food．The chips became so popular that the cook opened his own restaurant．

    When the weather is hot, you go to a lake or an ocean. When you are near a lake or an ocean, you feel cool. Why? The sun makes the earth hot, but it can not make the water hot. Though the air over the earth becomes hot, the air over the water stays cool. The hot air over the earth goes up, then the cool air over the water moves in and takes the place of the hot air. When you are near a lake or an ocean, you feel the cool air when it moves in. You feel the wind and the wind makes you cool.

Of course, scientists cannot answer all of our questions. If we ask "Why is the ocean full of salt?" scientists will say that the salt comes from rocks. When a rock gets very hot or very cool, it cracks (崩裂) , and rain falls into the cracks. The rain then carries the salt into the earth and the rivers. The rivers carry the salt into the ocean. But then we ask "What happens to the salt in the ocean? The ocean does not get saltier every year." scientists are not sure about the answer to the question.

    We know a lot about our world. But there are still many answers that we do not have, and we are curious(好奇的).

B

    All over the world in the twenty-first century, people can get new energy in many ways.

    Energy from the wind. People use the power of the wind．It is a clean source(来源) of energy, and there is lots of it. However, if the wind does not blow, there is no wind energy.

    Energy from the water. When water moves from a high place to a lower place, it has the power to make electricity. Waterpower produces enough energy for 40, 000 people in a town. Waterpower gives energy without pollution. However, people have to build dams(大坝) to use this energy, and building dams is very expensive.

    Energy from the earth. There is heat in the rocks under the earth. Scientists use the heat to make geothermal(地热的) energy. San Francisco gets half of the energy from geothermal power. This kind of energy is cheap, but it is only possible in a few places in the world.

    Energy from the sun. Solar panels(太阳能电池板) on the roofs of houses and buildings can turn energy from the sun into electricity. These panels can create enough energy to heat the whole house during winter. Solar power is clean and plentiful(丰富的), but when the weather is bad, it can't produce power．

    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.