动词不定式
结构 : to do (否定) not to do
动词不定式作用
Functions of Infinitive
1 主语  (subject) 2 表语  (predicative) 3 宾语  (object) 4 宾补  (object complement) 5 定语  (attribute) 6 状语  (adverbial) 7. 独立结构 (absolute construction)
三. 使用方法/ 功效
To see is to believe.It’s important to learn English well .
(1). 主语
句型转换To look after my pets properly takes a lot of time.It takes a lot of time to look after my pets properly .
My job    to help the patient.Your task   to clean the classroom.
is
is
(2). 表语