1.用在一些及物动词后,如wanttodofailtododecidetodomanagetodoplantodo

　　2.用在一些疑问词后可做主语,宾语,表语等.Whentostartisnotdecided.

　　3用在介词but后做介词宾语,如IdidnothingbutwatchTVyesterday./Wehadnochoicebuttowaithere.

　　4.用在动词后也可在句首做状语.如Hecametoseeme./To/Inordertocatchtheearlybus,hegotupearly.

　　5.用在系动词后做表语.如Mydreamistobeascientist.

　　6.用在句首做主语,Tobeasingerismydream.

　　7.用在名词或代词后做后置定语,ThebesttimetocometoBeijingisautume.

　　8.用在宾语后补充宾语做了什么,叫宾语补语

　　Ourteachertellsustoreadmoreinthemorning.

　　谢谢诶