不定式的一般体主动语态作表语的情况最为普遍，被动语态也可作表语。
My work is to clean the room every day. 我的工作是每天打扫房间。
His dream is to be a doctor. 他的梦想是成为一名医生。
What is hard is to do good all one's life. 难的是一辈子做好事。
What he feared most was to be found out. 他最不安的是自己的作为被人发现。
All he wanted was to be left alone. 他唯一的希望是不受打扰。
不定式的完成体和进行体同样可以作表语，完成体表示动作已完成，进行体表示动作正在进行中。
His achievement is to have produced a new method of calculation. 他的成就在于创造了一种新的计算方法。
All she wants is to be working with you. 她只要求和你一起工作。
句子的主语和表语都用不定式时，主语和表语之间往往有条件和结果（原因与结果）的逻辑关系。
To be kind to the enemy is to be cruel to the people. 对敌人的仁慈就是对人民的残忍。
To have read so much is to have been hard-working. 读了这么多书是刻苦用功的结果。
不定式的复合结构有时也可以作表语，复合结构的结构一般为：for+名词/代词+to do。
All that he wants is for somebody to be thinking about him. 他唯一的愿望是有人关心他。
“疑问词+不定式”结构也可以作表语。
The question is whom to send. 问题是派谁去。
作表语的不定式可以省略to吗？答案是肯定的。如果连系动词前面的主语部分含有实意动词do，作表语的不定式可以省略to，不定式对主语部分的do进行说明、补充、扩展或延伸，说明do的具体内容是什么。
All you have to do is wait for the right opportunity. 你现在需要做的事就是等待良机。
The best he could to was remain silent. 他所能做的最好的事就是保持沉默。
