1、非谓语动词作主语表示抽象概念用单数的谓语动词
Planting potatoes needs frequently watering。
Where to go is unknown to us.
3、and连接两个单数名词，指同一个概念
There comes the author and writer.
A Knife and folk is useful.
4、every...、and every.... 、each....、and each
5、强调句型中不管被强调部分
It is his classmates that helps him.
6、国、人名、书名、杂志、组织机构即使形式是复数
The United Nations is in American.
8、以s结尾，谓语动词用单数
如politics,maths,physics,economics(经济学）
9、either,neither作主语谓语动词用复数
Nether of us likes swimming.
13、表事物不定代词作主语：something,everything,anything,nothing
Is there everything wrong?
16、定冠词+形容词若表一类事物，谓语动词用单数
The new is sure to replace the old.
