题目

阅读理解 Music comes in many forms; most countrieshave a style of their own. The US is well known for jazz (爵士乐), which has gainedworld-wide popularity. In contrast to classical (古典的) music, which followsformal European traditions, jazz is natural and free-form. It is full ofenergy, expressing the moods, interests, and feelings of the people. It has a modernsound that makes people very excited. In the 1920s jazz sounded like America.And so it does today. The origins of this music are as interestingas the music itself. Jazz was produced by American blacks, who were brought tothe要得到y＝sin的图象，需将函数y＝sin的图象至少向左平移（　　）个单位．A． B． C． D.