African-Americans invented jazz at the beginning of the 20th century， so jazz has many features① of African music.
　　Improvisation② is one of its features. Improvisation means making something up as you go along. A jazz musician changes the words or tunes③ when he is playing. Different musicians， of course can play the same music differently. That is improvisation， and it makes jazz more fun to play and different from other music.
　　Now lets try to have an improvisation ourselves with “Happy Birthday to You”. First， sing it as we all know.
　　Happy birthday to you，
　　Happy birthday to you，
　　Happy birthday to my dear sister， Janet，
　　Happy birthday to you.
　　Now sing it again， but this time change the words and the tune a little.
　　Happy birthday to you， beautiful， so beautiful you，
　　Happy birthday to you， my so beautiful you，
　　...
　　Choose the best answer.
　　1. The underlined word “change” means “____” in Chinese.
　　A. 改變    B. 书写      C. 创作      D. 讲述
　　2. When did they invent jazz？
　　A. At the beginning of the 20th century. B. At the end of the 20th century.
　　C. At the beginning of the 21st century. D. At the end of the 21st century.
　　3. Which of the following is Not true？
　　A. Different people play the same music differently.
　　B. African-Americans invented jazz.
　　C. Jazz has many features of African music.
　　D. A jazz musician never changes the words or tunes when he is playing.
　　4. What is the main idea of the text？
　　A. Jazz is very popular. B. Jazz has many features.
　　C. Improvisation makes jazz fun to play and different from other music.
　　D. Happy Birthday to You is a very popular jazz song.