1. 表示文中的人说的话。"I've been thinking about this afternoon, you know,"said Halliday rather suddenly.2. 引用单词或短语。How do you spell the word "across"?3. 不寻常的词语也常用引号,以引人注意。The noun to which a relative pronoun refers is called the "antecedent" of the pronoun.关系代词