1、一般现在时中，复数做主语时，谓语动词be用are。如
They are students.
如果谓语动词是普通动词，则用原形。如
Tom and Jack go to school onfoot.
2、如果主语是单数时，动词be选择is或者am。如
I am a teacher.
He is a student.
如果谓语是普通动词，则用动词的第三人称单数形式。如
He goes to school every day.
Mike comes here.
3、在一般将来时，一般过去时，含有情态动词如can，must等时，主语是单数或复数时，谓语动词没有变化。如
He can ride a bike.
They can sing.
