一、人称代词he,she,it是第三人称单数.如：
He likes watching TV.他喜欢看电视.
She has lunch at twelve.她十二点吃午餐.
It looks like a cat.它看起来像只猫.
二、单个人名、地名或称呼作主语；是第三人称单数.如：
①Han Mei looks like her mother.韩梅看起来像她的母亲.
②Beijing is in China.北京在中国.
③Uncle Wang often makes cakes.王叔叔经常做蛋糕.
三、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.如：
①A horse is a useful animal.马是有用的动物.
②This book is yours.这本书是你的.
③That car is red.那辆小汽车是红色的.
④The cat is Lucy's.这只猫是露茜的.
四、不定代词someone,somebody,nobody,everything,something等及指示代词this,that作主语时,是第三人称单数.如：
①Everyone is here.大家到齐了.
②There is something wrong with the watch.这块手表有毛病.
③This is a pen.这是一支钢笔.
④That is an eraser.那是一块橡皮擦.
五、不可数名词作主语时为第三人称单数.如：
①The milk is in the glass.牛奶在玻璃杯里.
②The bread is very small.那面包很小.
六、当数字或字母作主语时,看作第三人称单数.如：
①"6" is a lucky number."6"是个吉利数字.
②"I" is a letter."I"是个字母.