1.动名词作主语的时候，谓语动词用单数。例：Sleeping is a relaxing thing.

2.动名词作主语，还可以是复合结构，前面可以有物主代词。例My opening the door anoyed him.

3.动名词短语作主语，这个短语又很长，这个时候往往用 it 做形式主语。例：It is no use telling him to keep clean.

4.动名词在There be结构中作主语。例：There is no knowing the future。