Here is a report from Xinghua Daily Newspaper. Computer games are very popular not only with the young people but also the adults. In some ways, they will take the place of (代替) the traditional games such as cards, chess and so on, because you only need a computer to play computer games. But in the past, if a man wanted to play chess, he must look for another one. In fact, computer games themselves are so interesting and exciting for us that the games can bring you happiness and excitement. They have been used in too many places such as schools, business, hospitals and so on.

    Now there are many educational games for the students. They are helpful to the students. They can make the students learn more and better by changing the study ways. When the students play the educational games, they use their brains (大脑), eyes, ears and hands. The students will be active (积极的) to get knowledge while playing. But now the students shouldn't spend too much time on the computer games. Otherwise (另外), it may affect their study.

    We have gone into the computer age. And learning too much knowledge through the computer is becoming true.

    In the eyes of many foreigners, Chinese are the best hosts (主人) and the worst guests in the world. They're not really bad guests, but because the guest-host relationship in China is much different than in some western counties, it appears they are not nice guests. And western guests sometimes look rude (粗鲁的) in the eyes of Chinese guests.

    In China, guests are almost like gods. Whenever I enter a Chinese person's home, there is always fruit on the table for me, and someone is quick to bring me a cup of tea or water. In the west, generally the guest is not a god. Acting according to the host's way of doing things is usual behavior for a guest.

    My wife's mother, a very kind elderly Chinese lady, doesn't smoke. When I see some of her guests smoking in her house, as a non-smoker, I feel unhappy. Usually I want to stop them directly, but I must realize that in China, to be a good host, she must not do that. In most North America homes, if you are a guest, and the hosts are not smokers, you should not smoke in their house. At the very least, you could ask, “Is it OK if I smoke?” “But, don't be surprised if they say, “No, you can't smoke.” In our culture, if you smoke in their home, you are a bad guest, but if they don't allow you to smoke in their house, they are not a rude guest.

    Guests in China also have special habits. Some western people may not adapt to these habits very soon. Thankfully my wife is Chinese, so whenever we visit a Chinese family she tells me to buy them a gift. However, giving a gift to a host is not always necessary in my country. So, if you invite international guests to your home, don't be too surprised if they don't bring you a gift.

    In China, you probably won't need to change the guest-host relationship very much because you will probably only be the host, and Chinese are naturally very good hosts. If western hosts invite you to their house, try not to be too surprised if their style of treating you is not what you have expected.

关于速度和加速度的关系，下列说法正确的是（  ）