unit 1-3语法-不定式 to do1不定式的基本形式与结构动词不定式指通常由to加上动词原形 (如to write) 所构成的一种动词形式，但在有些情况下to可以省略。所有的主动词，不论是及物动词还是不及物动词，都有不定式形式。没有不定式形式。动词不定式在语法功能上可作主语、宾语、表语、定语和状语。2不定式的用法1)不定式结构作主语1.Te get contact with his family in Taiwan made him extremely happy since they separated more than 40 years ago2.To finish that task in such a short time is really a challenge在上述情况下，如果不定式较长，显得头重脚轻，则可由代词让作形式主语(形式主语it不可由that或this等其他代词代替)，而将不定式放到后面。如：1.It made him extremely happy to get contact with his family in Taiw
