根据短文内容，从题中所给的A、B、C、D四个选项中选出最佳答案。

     If you like to check your smartphone from time to time, you are not alone. In fact, using apps（应用程序）has now become part of everyday life.

Changba

      Changba, which has been described as "the best mobile karaoke for sound", allows you to sing along to over 2,000 songs. You can also share your KTV recordings with friends on social media sites such as Weibo, Wechat, Qzone, etc. The app allows users to create a photo show to go with their songs and comment on other people's songs. Changba can even filter the sound. For example, it can make cat noises sound like a beautiful chorus(合唱).

Moment Cam

     Moment Cam brings you some of the most useful features a camera app can have, such as adjusting the flash(调整闪光灯）,continuous shots, adjusting the timer, and choosing different sizes for photo-sharing sites. But what sets the app apart from all the others is the choice of simple mini-buttons that you hardly notice are there.

Carrot

     Carrot, a to-do list app, is a task manager with a personality, When you succeed in finishing your tasks, for example, Carrot praises you with a message such as "Way to go. Soon you'll be completing other people's to-do lists".But if you fail to perform your tasks, Carrot might say, "I'm angered at your behavior." And it may change its background from white to black to show how angry it is. So, if you need an extra push to finish your tasks, give Carrot a try.

    All living things on the earth need other living things to live. Nothing lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another, one eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain (食物链). Some food chains are simple, while others are not. But all food chains begin with the sun, and all food chains become broken up if one of the links (联系) disappears.

    All life needs sunlight to live on. But only plants can use sunlight directly (直接). Plants are “factories”. They make food from sunlight, water and things in the soil (土壤) and air.

    Plants feed all other living things. Animals can only use the sun's energy (能量) after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly.

    What about human beings? We are members of many food chains. We eat wheat (小麦), rice, vegetables, fruits and so on. We also eat meat and drink milk. But humans often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them cannot be eaten. If men eat the fish, they will get strange diseases (疾病).

    Each form of life is linked to all others. Breaking the links puts all life in danger.

    Kate is reading something about how to keep healthy on the Internet.

    Good sleep is important for your health. You need about eight hours' sleep a night. Don't eat or read in bed. A cup of milk before sleeping may help you get a good sleep. Go to bed before 10: 00 and get up early every morning. For more information, please visit www.sleeping.com.

    How often do you exercise? If you want to stay healthy, you should do a lot of exercise. Try to exercise for 30 minutes a day, three or four times a week. For more information, please call Health Line at 180–2000.

    Studies show that the cold or flu virus（病毒） can live on our hands for long. So you should wash your hands often with soap and water. If you want to know more, please call Health Line at 180–1313.

    Brush your teeth twice a day and see a dentist at least once a year. The oral examination（口腔检査） is not only for the health of teeth, but the whole body. Please visit www.mydr.com for more information.

    Why do we like drinking water from plastic bottles? Some people think it is healthy and clean. Others drink bottled water because it's easy—you can carry it around with you. In hot countries, like Greece, we often buy bottles of cold water in summer.

    However, making lots of plastic is not a good idea for many reasons. First of all, we need a lot of oil for plastic products. We usually use oil as a source(资源) of energy. If we reduced the number of bottles we made, we wouldn't need so much oil. Plastic bottles also pollute the environment. If we recycled all our plastic bottles, we wouldn't need so much space for rubbish dumps. But in Greece, we don't recycle much of the plastic we use. In 2006, Greeks recycled only about 10% of plastic waste. The rest became rubbish on land and in rivers and seas.

    So next time you want to throw away a plastic bottle in the litter bin, stop and think. If you recycled it, you would help the environment. But what can you do when there isn't a recycling bin near you? Well, there are lots of useful ways that you can use your bottles again. For example, an empty bottle makes a great piggy bank for your pocket money, and if you cut a bottle in half, you will have a plant pot. Go green! You can make a difference.