阅读理解 Different countries and different people have different manners. We must find out their customs so that they will not think us ill-mannered(没有礼貌的). Here are examples of the things that a person with good education does or does not do. If you visit a Chinese family, you should knock at the door first. When the door opens, you will not move before the host says 'Come in, please.' After you come into the room, you would not sit down until the host asks you to take a seat. When a cup of tea is put on a table before you or sent to your hand, you will say 'thank you' and receive it with two hands. not one hand or they will think you arc ill-mannered. Before entering a house in Japan, it is a good manner to take off your shoes. In European countries, even though shoes sometimes become very dirty, this is not done. In a Malay house, a visitor never finishes the food on the table. He leaves a little to show that he has had enough. In England, a visitor always finishes the drink or the food to show he has enjoyed it. That will make the host pleasant. 根据短文内容，回答下列问题 1. Does the writer think it is necessary to know different customs in different countries? 2. When can you enter the room if you visit a friend in China? 3. What should you say when a cup of tea is sent to your hand? 4. In which country do you have to take off your shoes when you enter the host's house? 5. Why does a visitor always finish the food at dinner in his friend's home in England?