用法:1. 习惯性、经常性的动作或存在的状态
I often get up early. He is busy every day.
2. 主语的特征、性格、能力、爱好。
She is tall. I like swimming. John works hard.
3. 客观真理
There are seven days in a week. The earth moves around the sun.
结构:1. 主语+系v. :be后不跟其他v.,常跟adj. n. prep短语做表语.
2. a. 主语+v.原形:主语为第三人称单数以外的其他人称
变特殊疑问句:主语前+do,后跟v.原形
否定:主语+don't+v.原形
b. 主语(三单)+其他v.:
1. 一般v.末尾+s:likes
2. 以辅音+y结尾,变y为i+es:flies,studies
3. s,x,ch,sh,o结尾,v.末尾+es:teaches
变特殊疑问句:主语前+does,后跟v.原形
否定:主语+doesn't+v.原形