主语的定语是修饰主语的词、短语或句子. (1)介词短语作定语:The boy in blue is Tom.穿蓝色衣服的孩子是汤姆. (2)名词作定语:It is a ball pen.这是一支圆珠笔. (3)副词作定语:The best boy here is Tom.这里最棒的男孩是Tom. (4)不定式作定语:There is nothing to do today.今天没有事要做. (5)分词(短语)作定语:There are five boys left.有五个留下的男孩. (6)定语从句:The boy you will know is Tom.你将认识的男孩叫汤姆.