主谓一致的三条原则
1、语法一致，即在语法形式上取得一致。
Human beings enjoy learning.
Everybody’s understanding is incomplete.
2、意义一致，即根据意义来处理一致关系。
The people there are fighting for the independence of their country.
Ten dollars was a lot of money at that time.
3、就近原则，即谓语动词的单、复数形式取决于最靠近它的词语。
There is a pen,two pencils and an eraser in the pencil box.
Neither the boy nor his teachers know the answer.