动词单三变化规则
1.一般情况下，直接在动词词尾+s：
2.以s，x，sh，ch，o结尾的动词，在词尾+ es：
3.以辅音字母+ y 结尾的动词，先把y变为i，再加es：
4.不规则动词（特殊情况）：
变否定句时遵循的规则
含有动词第三人称单数形式的.句子变否定句时，要在动词前面加上doesn’t 或does not，动词的第三人称单数形式要还原成原形：格式为doesn’t/does
not+ 动词原形，如：
He goes to school at six in the morning. (变否定句) 就变换为：
He doesn't go to school at six in the morning.
2.变一般疑问句：把含有动词第三人称单数形式的变成一般疑问句时，要借用助动
词does，如：
She goes home at five every day.（变疑问句）就变换为：
Does she go home at five every day? -- Yes，she does./No，she doesn’t.
哪些主语是第三人称单数
1.人称代词he，she，it；
如：He likes watching TV.
She has lunch at twelve.
It looks like a cat.
2.单个人名、地名或称呼作主语；是第三人称单数。如：
Han Mei looks like her mother.
Beijing is in China.
Uncle Wang often makes cakes.
3.单数可数名词或
this/that/the+单数可数名词作主语时，是第三人称单数；
A horse is a useful animal.
This book is yours.
That car is red.
4、不可数名词作主语时为第三人称单数。如：
The milk is in the glass.
The bread is very small.
The water is very cold.