在gmat考試中，不定式，如as to watch, to throw, 和to see是動詞最基本的形式。不定式能做名詞、形容詞和副詞。下面隨本站小編來看看詳細的不定式語法解讀吧!
Noun(作名詞): I love TO SWIM. To swim是動詞love的賓語。
Adjective(作形容詞): The person TO MEET is here. To meet 修飾名詞person。
Adverb(作副詞): Sue paused TO EAT lunch. To eat修飾動詞paused，表示目的。
上面第三個句子，不定式表示目的：why she paused or for what。這個句子也可以寫成：Sue paused in order to eat lunch.
in order to不wordy，儘管有同學認為這個短語相對於to來說wordy。無論是否用短語in order to，要注意它們表示目的的作用。看下面這個例子：
Right: The contractors DEMOLISHED the building to keep it from falling down accidentally.
動詞demolished的主語是名詞contractors，同時contractors也是不定式to keep的隱式主語(implied subject)，動詞不定式to keep在這裡表示demolished的目的，keep的賓語代詞it的先行詞是building。
Wrong: The building WAS DEMOLISHED to avoid falling down accidentally.
在這個例句中動詞was demolished的主語是building，同時building也是不定式to avoid的隱式主語，但是a building自己不能avoid something intentionally。所以上面的例句是無意義的'(nonsensical)。
再看下面這個例句
Right: The building WAS DEMOLISHED to keep it from falling down accidentally.
這個例句的主語是building，同時building也是不定式to keep的隱式主語，但是代詞it是不定式to keep的賓語，指代building。由於building是不定式to keep的賓語，所以上面的寫法也是正確的，表示的意思是the same unnamed people who demolished the building wanted to keep it from falling down accidentally.
注意，不定式雖然能做動詞，但是不是名詞結構。所以，雖然不定式能夠做主語，但是一般來說，GMAT語法用代詞it來指代主語，放在句首。
動名詞(gerunds)-ing作名詞，與不定式相比，動名詞更像名詞結構，所以動名詞既能做動詞的賓語，又能做動詞的主語，還能做介詞的賓語。如以下例句：
Subject of verb(作動詞的主語):SWIMMING is fun. Swimming是is的主語。
Object of verb(作動詞的賓語): I love SWIMMING. Swimming是love的賓語。.
Object of preposition(作介詞的賓語): I dream of SWIMMING. Swimming是介詞的賓語。
我們在chapter 11中學過，動名詞分為一般動名詞和複雜動名詞，動名詞前面有冠詞的是複雜動名詞。看以下例句
Simple gerund: EATING apples quickly (more verb-like，更像動詞)
Complex gerund: The quick EATING of apples (more noun-like，更像名詞)
記住，一般動名詞與複雜動名詞不能平行，同時當相應的動作名詞存在時不要用複雜動名詞，即the quick consumption of apples(動作名詞)比thequick eating of apples(複雜動名詞)好。
如果名詞是動名詞所表示動作的行使者，那麼這個名詞必須是所有格的形式，如以下例句
Wrong: Mike SWIMMING is the product of new coaching techniques.
Right: Mike's SWIMMING is the product of new coaching techniques.
在用以上規則時，要檢查下，動名詞是否是名詞?還是名詞的修飾詞，有時兩種用法都說得通，如以下例句
Suspect: I like Mike SWIMMING. (=名詞修飾語 I like Mike only as he swims, not as he runs? 當Mike游泳時，我喜歡他?OR 名詞I like for him to be swimming rather than lifting weights?我喜歡Mike去游泳)
可以改成以下句子來避免歧義
Right: I like Mike's SWIMMING. (名詞= I like his swimming itself.)
Right: Mike SWIMMING is a sight to behold. (名詞修飾語Mike himself can be the sight.)
Right: Mike's SWIMMING is a sight to behold. (The swimming can be the sight.)
