题目

The first Europeans came to America in 1492 with Christopher Columbus. Since that time people have come to America from all over the world, from Europe, Africa, and Asia, and they have brought their music with them. This mixing of people and music has created American music. Music is a very important part of our lives. Music is for dancing, drinking, eating, loving, and thinking. Some songs remind us of our childhood or youth. Others remind of the people they love. Many important occasions, like weddings and funerals have special music. Every nation has a national song like the American 已知向量，，，若为实数，，则A． B． C．1 D．2