动词不定式动词不定式形式:一般式完成式进行式完成进行式主动tobuildtohavebuilttobebuildingtohavebeenbuilding被动tobebuildtohavebeenbuild动词不定式的主要用法:一、作主语⒈不定式作主语动词不定式作主语时,句子的谓语动词常用单数,其位置有以下两种:(1)把不定式置于句首
如:Togettherebybikewilltakeushalfanhour
(2)用it作形式主语,把真正的主语不定式置于句后,常用于下列句式中
如:①It+be+名词+todoIt‘sourdutytotakegoodcareoftheold
②Ittakessb+sometime+todoHowlongdidittakeyoutofinishthework
③It+be+形容词+forsb+todoItisdifficultforustofinishwritingthecompositioninaquarterofanhour
④It+be+形容词+ofsb+todoItisstupidofyoutowritedowneverythingtheteachersays
⑤Itseems(appears)+形容词+todoItseemedimpossibletosavemoney
二、作宾语⒈不定式作宾语①以下动词后,只能跟不定式作宾语
如:agree,ask,aim,arrange,choose,decide,demand,expect,fail,help,hope,lean,long,manage,offer,plan,prepare,pretend,promise,refuse,wish等如:Idecidedtoaskformymoneyback
②当复合宾语中的宾语是不定式时,先用形式宾语it代替不定式,把不定式置于补语之后,即:主