用法：
1、be+名词：
The man is a science teacher.
这个男子是一位科学教师。
Bill Clinton was the president of the US.
比尔克林顿是美国总统。
2、be+形容词或副词：
This soup is very tasty.
这汤很美味。
Mary’s new dresses are colourful.
玛丽的新衣服色彩鲜艳
3、be+动词ing形式连用表持续：
We were walking down the street.
我们正走在街上。
My mother is watching TV in the room.
我妈妈正在房间里看电视。
4、be+介词短语：
John and his wife are from Manchester.
约翰和他的妻子来自曼彻斯特。
The flowers are on the table.
花在桌子上。