题目

Americans use many expressions with the word dog. People in the United States love their dogs and treat them well. They take their dogs for walks, let them play outside and give them good food and medical care. However, dogs without owners to care for them lead a different kind of life. The [Z-X-X-K]expression, to lead a dog’s life, describes a person who has an unhappy life. Some people say we live in a dog-eat-dog world. That means many people are competing for the same things, like good jobs. They say that to be successful, a person has to work like a dog. This means they have to wo下列现象能说明分子间存在吸引力的是（ ）A．固体和液体很难被压缩B．红墨水滴入水中很快散开C．酒精和水混合后总体积变小D．两个表面光滑的铅块紧压后会“粘”在一起