题目

Ⅱ. 语言知识及应用（共两节。满分35分） 第一节  完形填空（共10小题；每小题2分，满分20分） 阅读下面短文，掌握其大意，然后从21~30各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。 In 1933 an unknown American called Clarence Nash went to see the film-maker Walter Disney. He had a(n)    21    voice and he wanted to work in Disney’s cartoon film for children. When Walter Disney heard Nash’s voice, he said, “Stop! That’s our    22   .” Disney declared Nash perfect for the role of a如果用字母a表示一个有理数，那么-a表示怎样的有理数？请你简单地说明理由．