分几种情况.首先一般是跟doing,表现在进行时；例如：I am jogging.
还可以跟动词的被动形式表被动;例:The clothes were washed by my mother.
还可以接动词不定式,表示将来；例：She is to be married with Bob.
翻译：My dream is to be a doctor.I think it is quite great to be a doctor.
好好看看语法书,这一部分并不难,