1.问句的第一人称代词用I.Am I...
第二人称代词用you /they.Are you...Are they...
第三人称代词用he、she、it Is he/she/it...
2.主语为you,they,或复数名词的时候用are
比如说 Are you crazy?
Are the girls pretty?
Are those apples red?
主语为he /she/ it 或者单数名词时 用is
比如说 Is the dog big?
现在进行时：Are you walking?（表示正在进行的动作）
ls she/he/it walking?
一般现在是：主语为She/He/It或单数名词时 动词要加s 助动词do加es
主语为复数时 不加s
Does She /He/ it like the flowers?
Do children like flowers?（主语为复数,所以动词不加s）