動(dòng)詞不定式就是我們常說(shuō)的to do形式，其中的動(dòng)詞是以原形出現(xiàn)的，情態(tài)動(dòng)詞加動(dòng)詞原形就是因?yàn)榍閼B(tài)動(dòng)詞要求接不帶to的不定式，也就只剩動(dòng)詞原形了。
分詞包括過(guò)去分詞和現(xiàn)在分詞，拿fall為例，fallen為過(guò)去分詞，falling為現(xiàn)在分詞。fallen leaves表示落葉（在地上），falling leaves表示落葉（正在下落）。
動(dòng)名詞的形式與現(xiàn)在分詞是一樣的，但是意義上稍有區(qū)別，例如：
a sleeping bag，這里的sleeping是動(dòng)名詞，表示的是a bag for sleeping.
a sleeping baby,這里的sleeping是現(xiàn)在分詞，表示的是a baby who is sleeping動(dòng)詞不定式概述
一 不定式的體
1. 不定式的一般式(to do)表示不定式的.動(dòng)作將要發(fā)生或與謂語(yǔ)動(dòng)作同時(shí)發(fā)生.
2 不定式的進(jìn)行體(to be doing)表示不定式的動(dòng)作正在發(fā)生.
不定式的完成體(to have done)表示不定式的動(dòng)作在謂語(yǔ)動(dòng)作之前發(fā)生.
二 不定式的邏輯主語(yǔ)
1 不定式的邏輯主語(yǔ)常不出現(xiàn)在句中.
2 句子的主語(yǔ),賓語(yǔ)有時(shí)是不定式的邏輯主語(yǔ).
3 不定式前"for+名詞/代詞"結(jié)構(gòu)中的名詞或代詞也可以用來(lái)表示不定式的;邏輯主語(yǔ).
4 在"It+be+形容詞+of+名詞/代詞+to do"結(jié)構(gòu)中,名詞或代詞為不定式的邏輯主語(yǔ).該結(jié)構(gòu)中的形容詞通常用來(lái)表示人的品質(zhì).例如:kind, good, nice, bad, cruel, honest, bold, thoughtful, right, wrong, wise, clever, silly, foolish, careless, rude等.
例如:It's very kind of you to cal to tell me about the conference.
三 不定式的否定式
不定式否定式由not/never +to do構(gòu)成
四 不定式的句法功能
1 不定式做主語(yǔ)
1)To say something is one thing; to do it is another.
2)It is not a good idea to build houses along the lines where two of the earth's plates join together.
注:充當(dāng)主語(yǔ)的不定式即可置于句首,位于謂語(yǔ)動(dòng)詞之前,也可作為句子的真正主語(yǔ)置于句末,用作形式主語(yǔ).
2 不定式作表語(yǔ)
3)Her uncle seems to be acting rather strangely towards her these days.
4)The purpose of the fence is to keep out a type of wild dog called a "Dingo".
5)One suggested answer is for farmers to limit the number of their cattle.
注:充當(dāng)表語(yǔ)的不定式一般位于be ,seem等系動(dòng)詞后.
3 不定式作賓語(yǔ)
6)Shylock agreed to lend Antonio money on one condition.
注:充當(dāng)賓語(yǔ)的不定式位于及物動(dòng)詞后.常用不定式作賓語(yǔ)的動(dòng)詞有:agree, plan, determine, dare, refuse, hope, wish, expect, promise, choose, pretend, decide, manage, intend, offer, afford, demand.
7)The dusty air makes it difficult to get a clear picture of space.
注:充當(dāng)賓語(yǔ)的不定式如果有自己的表語(yǔ),則可用代替只個(gè)不定式作為形式賓語(yǔ),而作為真正賓語(yǔ)的不定式則放在表語(yǔ)之后.以it作為形式賓語(yǔ)的這種結(jié)構(gòu)常用在think, feel, find, make, consider等動(dòng)詞之后.
big and strong.
4 不定式作賓語(yǔ)補(bǔ)足語(yǔ)
8)The powder made from fish, blood and bones will make the cabbage plants grow big and strong.
9)Portia told Bassanio to go to his friend at once.
注:在下列動(dòng)詞后作賓語(yǔ)補(bǔ)足語(yǔ)的不定式通常不帶to.這些動(dòng)詞是observe, notice, see, hear, watch, have, feel, make, let.但上述動(dòng)詞轉(zhuǎn)換為被動(dòng)語(yǔ)態(tài)時(shí),其后的不定式須帶to.例如:The cabbage plants will be made to grow.