系动词
表语
表语：用来补充说明主语形状、大小、状态、在哪里、是什么。
I am a student. 表语是名词“a student”, 补充说明主语的职业。
Her mother is beautiful. 表语是形容词“beautiful”, 补充说明主语的状态。
They are hungry. 表语是形容词“hungry”, 补充说明主语的状态。
The cat is in the living room. 表语是指地点的介词词组“ in the living room”, 补充说明主语的地点。
He is ten. 表语是数词“ten”, 补充说明主语的年龄。
It is* a book. 表语是名词 “a book”, 补充说明主语是什么。
状态类
单独使用的Be（区别于 am studying 等做语法功能）
It
isnice!That
isgood!He
isill.This apple
isgood.Those cakes
aredelicious.
感官类
看起来
look： Itlooksnice!听起来
sound： Thatsoundsgood!摸起来
feel： Hefeelsill.闻起来
smell： This applessmellsgood.尝起来
taste： Those cakestastedelicious.
He looks tall. = He is tall.
“看起来”是“别人看他, 是别人的感观“，不是主语发出的动作。是外部感官到的 主语的状态。
渐变类
- get 译为：变得
- become 译为：成为
- turn 译为：变成了
- keep 译为：保持
It is getting warm. （主系表，get是系动词，is是语法作用助词）
渐变类系动词强调主语的状态是渐渐变成的，表语成分由名词或形容词充当,补充说明主语的状态。
There be
There be + n + 介词短语
There is a girl in the classroom.There be + n + doing
There is a girl crying.
Some children were playing games on the bank and there were some people rowing on the rivers.