no=not a\not any。 例如: There isn't a bird in the cage. There is no bird in the cage. 以上两句意义相同。 There aren't any books on the desk. There are no books on the desk. 以上两个意义同。 对一般现在式的谓语动词进行否定,要用到don't或doesn't。 They don't live in the same city. 他们没有生活在同一座城市。