题目

When you are about to do something brave, a cheerful wish of “Good luck!” from a friend can be helpful. But if you think you need lots of luck, what else might you do?In the UK and US there are some strange traditions for bringing yourself a little more good luck. Some are hundreds of years old and some are much newer.Have you heard the saying “When you wish upon a star”? If you are looking up at the sky on a clear night and you see a sudden flash of light, it is probably a shooting star! Seeing one doesn’t happen very often. The saying goes that if you see one you have been very luc下列不会造成空气污染的是（　　）A．工业废气排放B．汽车尾气C．地面扬尘D．人和动物呼出的气体