动名词做表语通常是指经常反复发生的事情。不定式做表语通常是指具体某次的事情。把动名词或者不定式提前做主语一个意思。
My hobby is collecting stamps.=Collecting stamps is my hobby.(经常）
My dream is to go to college.=To go to college is my dream.(具

动名词做表语指一般的情况  二不定时表某一具体情况 或没有发生的事

不定式表将来和目的，动名词表示正在进行或将要（打算）做某事。

不定式、动名词、分词做表语： 

1、不定式做表语常表示谓语动词所表示动作之后发生的动作。不定式一般紧跟在系动词如: be, seem, remain, appear等后面, 用来说明主语的内容。这类结构中的主语一般为名词，如：idea, purpose, hope, plan, intention, wish, dream, etc. 

eg.) My purpose is to teach them a lesson. 

有时句子主语也可以是不定式或名词性从句。 

Eg.) To be strict with students is to be responsible to them. 

What I want to do is (to )tell you the truth. 

The only thing he could do was ( to) tell the truth. 

如果主语中含有do的任何形式, 那么不定式可以省去to. 


2、动名词做表语是对主语内容的解释，这时主语与表语位置可互换，动名词常用于口语中。 

Its full-time job is laying eggs. 

3、分词做表语: 

现在分词作表语:一般表示主动或主语的性质和特征, “令人……”的, 主语多数情况是sth. 

过去分词作表语: 一般表示被动或说明主语情感心理上的感受, “感到……的”,主语多数是sb. 

exciting, excited annoying, annoyed amazing, amazed 

boring, bored confusing, confused encouraging, encouraged 

embarrassing, embarrassed frightening, frightened; inspiring, inspired 



现在分词做表语表示主语的性质与特征；进行时表示正在进行的动作。 

The task of this class is practising the idioms. （现在分词做表语） 

With the help of the teacher, the students are practising the idioms. （现在进行时） 

过去分词作表语表示主语所处的被动状态或完成某动作的状态。而被动语态表示主语所承受的动作。 

The village is surrounded by high mountains.（过去分词做表语） 

The enemy was surrounded by the Red Army.（被动语态） 

He is well educated.（过去分词做表语） 

He has been educated in this college for three years.（被动语态）