文档介绍：不定式用法
使用时需要注意:
,  hear,  listen to 等感观动词和 have, let , make等使役动词后的补足语,在主动语态中,不定式不带to;在被动语态中,则必须带to。如:
I often hear him sing the song. / He is often heard to sing the song.  
2. 不定式短语位于介词but, except, besides后时,如果这些介词之前有行为动词do 的各种形式,那么,这些介词后的不定式不带to,否则要带to。如:
She could do nothing but cry. / It has no choice but to lie down and sleep.
使用时需要注意:
3. 不定式修饰的名词或代词与不定式逻辑上构成主谓关系时,不定式往往用主动形式。如:
 Have you got a key to unlock the door? (A key unlocks the door.)
4. 不定式和它前面被修饰的名词或代词构成逻辑上的动宾关系,又和该句的主语构成逻辑上的主谓关系时,不定式常用主动形式。如:
I have got a letter to write.( I write a letter.)
,且和句中主语构成逻辑上的动宾关系时,不定式多用主动形式。如:
The book is difficult to understand.( to understand the book)
admit, appreciate, avoid, consider等动词后一般用动词-ing形式做宾语。
3. 在allow, advise, forbid, permit等动词后直接跟动词作宾语时,要用动名词形式;如果其后有名词或代词做宾语,然后再跟动词作宾语补足语时,其宾语补足语用带to的不定式。如:
We don’t allow smoking here. / We don’t allow students to smoke.
To do & doing
不定式和动词-ing形式都可以做主语,动词-ing形式做主语表示一般或抽象的多次性行为;不定式做主语往往表示具体的或一次性的动作。如:
Playing with fire is dangerous.(泛指玩火) / To play with fire will be dangerous.(指一具体动作)
作主语(a)、宾语(b)、表语(c)、定语(d)或是状语(e)
scold her would not be just. 责备她是不公平的。
are planning to build a reservoir here. 我们计划在这里修一座水库。
of our main tasks now is to mechanize agriculture. 我们当前的主要任务之一是实现农业机械化。
you have anything to declare? 你有什么要申报吗?
e. We e to learn from you. 我们是来向你们学****的。
主动形式被动形式
一般式 to do; to be done;
完成式 to have done; to have been done;
进行式 to be doing; ________
完成进行式 to have been doing; _________
不定式作主语:
To persevere means victory! 坚持就是胜利!
plete that building in ten months was a great achievement. 那座楼10个月就盖成是一个了不起的成就。
To ignore this would be a mistake. 忽视这一点是错误的。
To see is to believe. 眼见为实。
To act like that is foolish. 这样做是愚蠢的。
To err is human, to forgive divine. 犯错误是人之常情,宽恕才难能可贵。
To know something about English is one thing; to know English is quite another. 懂一点英语是一回事;掌握英语完全是另一回事。
不定式作主语
It isn't right to gossip about others. (=To gossip about others isn't right.) 说闲话是不对的