times 主语
are changing 谓语（现在进行时）
翻译：时代正在改变.
主系表结构的表语部分通常为形容词,有时候也可以是名词,副词,介词短语等,但是很少能是动词.
比如 she is beautiful.
i am here.
The book is on the table.
this is my book.