修饰主语的语叫做 定语。定语是用来描述、限定或说明主语的特征、性质、状态等的成分，通常位于主语之前。在中文和英文中，定语的位置和作用与形容词相似，都是用来修饰名词或代词，使句子更加具体和生动。例如：

1. The thickbook is mine.

2. The threedollars are enough.

3. The manover there is my father.

Doingmorning exercises is necessary every day.

Brokenglass is dangerous.

6. The buildingto be built next year is a new project.

在这些例子中，“thick”、“three”、“man”、“Doing”、“broken”和“building”都是定语，它们分别修饰了主语“book”、“dollars”、“man”、“morning exercises”、“glass”和“building”。