题目

The power of humor and laugher is numerous. They entertain us and make us feel good. But, above all, we have discovered that humor and laughter are the best medicine. They relieve pain, reduce stress and anxiety, and are anti-aging and longevity facilitators. They are extremely necessary for helping us to find and maintain a balance between life and work. However, they are slipping away from us. We have become far too serious. The only ones who still enjoy humor, laughter, fun and play to the fullest are young children. Children tend to laugh an average of 200 times a day. For adults下列关于位移与路程的说法中，正确的是（   ）A．位移和路程的大小总相等，但位移是矢量，路程是标量B．位移取决于始、末位置，路程取决于实际运动的路径C．质点通过的路程不为零，但位移可能为零D．只有质点做直线运动时，它通过的路程就是位移大小