听力原文： American restaurant customs are in some ways different from those in other countries. It may be appropriate to get a waiter or waitress' attention by calling, whistling or snapping the fingers while in other countries. In America, you put up a finger to catch his or her eyes. In many parts of the world a fixed service charge is added to restaurant bills. In most American restaurants it is common to tip the waiter or waitress about 15% of the total bill. If the service was very good, you can leave a larger tip. If it was bad, you may leave less. The tip is usually left on the table, but you can also give it directly to the waiter or waitress. In better restaurant you pay your bill through the waiter or waitress. In expensive ones you pay it by yourself. Finally, if you are not able to finish your food, it is perfectly acceptable to ask for a 'doggie bag' for the extra food. If you want to get served in an American restaurant, how can you get your service?