非謂語動詞�？嫉钠渌Y(jié)構(gòu)
(1)疑問詞+不定式結(jié)構(gòu)
疑問詞who，what，which，when，where和how后加不定式可構(gòu)成一種特殊的不定式短語。它在句中可以用作主語、的賓語、的表語和雙重賓語。如：
When to start has not been decided.何時動身尚未決定。(主語)
I don’t know what to do.我不知道該怎么辦。(賓語)
The difficulty was how to cross the river.困難在于如何過河。(表語)
I can tell you where to get this book.我可以告訴你哪里可以買到此書。(雙重賓語)
(注)A.有時疑問詞前可用介詞，如：
I have no idea of how to do it.我不知道如何做此事。
B.動詞know 后面不能直接跟不定式作賓語，只能跟疑問詞(如：how, what)+不定式：
While still a young boy, Tom knew to play the piano well and as he grew older, he wrote operas, the most famous of which is Carmen.
(2)介詞except和but作“只有…，只能…”講時跟不定式結(jié)構(gòu)(but與不帶to的不定式連用)。
When the streets are full of melting snow, you cannot help but getting your shoes wet.
(3)不帶to的不定式
1)在表示生理感覺的動詞后的不定式不帶to。這類詞有：
feel 覺得 observe 注意到醫(yī)學全在,線f1411.cn，看到 overhear聽到
watch注視 listen to聽 perceive察覺，感知
notice注意 see看見 look at看 hear聽
On seeing the young child fell into the lake，Eric sprang to his feet，and went on the rescue.
2)另一類是某些使役動詞，如make, let，have等。如：
Let him do it.讓他做吧。
I would have you know that I am ill.我想要你知道我病了。
