非谓语动词解析2

二、不定式
1、动词不定式形式:（to）+do具有名词、形容词、副词的特征;否定式:not+（to）do
2、不定式的句法功能:
（1）作主语:
To finish the work in ten minutes is very hard.
To lose your heart means failure.
动词不定式短语作主语时,常用it作形式主语,真正的主语不定式置于句后,例如上面两句可用如下形式:
It is very hard to finish the work in ten minutes.
It means failure to lose your heart.
常用句式有:
1、It+be+名词+to do.
2、It takes sb.+some time+to do.
3、It+be+形容词+of sb+to do.
4、It+be+形容词+for sb.+to do.
常用careless,,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise,等表示赞扬或批评的形容词,不定式前的sb.可作其逻辑主语.
（2）作表语:
Her job is to clean the hall.
He appears to have caught a cold.