Different 是后置定语,修饰words and expressions. 如果填are different就会使从句多出一个谓语动词,这样就犯语法错误. 其中 be different from 是词组,"与...不同".这类的词组很多,如be good at. 举个例子:He is a man good at playing basketball. good 修饰man.
When people use words and espressions different from "standard English",这是一句话,different from "standard English"是修饰 words and espressions ,是定语,不是独立的一句话。而且如果是When people use words and espressions are di...