在一般情況下,too...to...結構意為“太……以致不能……”,too后接形容詞或副詞,to是動詞不定式符號,后接動詞原形,動詞不定式表示否定意義.但是,too...to...結構在以下情況中,動詞不定式表示肯定意義.
一、too...to ...的意義
too...to...句型形式是肯定的,但表達否定意義,表示"太……而不能……".too的后面接形容詞或副詞的原級,to的后面接動詞原形,構成動詞不定式.too...to...句型是簡單句.例如：
He is too young to join the army.他年齡太小,不能參軍.
二、動詞不定式的邏輯主語
動詞不定式所發(fā)出的動作,其執(zhí)行者與整個句子的主語不同指一個人或物時,需要在動詞不定式前加上一個邏輯主語(for sb.).例如：
The maths problem is too difficult for me to work out.這道數(shù)學題太難我不能解出它.
三、too...to...結構表示肯定意義的情況
1.too前面含有表示否定意義的詞,例如:not,never,nothing等時,too...to...結構不表示否定意義.例如：
One is never too old to learn.活到老,學到老.
2.如果在too...to...結構的前面出現(xiàn)了only,不僅免去了其否定意義,反而加強了它的肯定語氣,only too相當于very或very much.例如：
I shall be only too pleased to get home.我將極高興地回家.
3.too后為表示情感的形容詞,例如：glad,pleased,happy,sad等時,表示的是肯定意義.例如：
He is too sad to hear the bad news.聽到不幸的消息他太悲傷了.
四、too...to...結構與...enough to...結構及so...that...結構的相互轉換
1.將too...to...結構轉換為...enough to...結構時要注意：①enough前的形容詞或副詞須是too前面形容詞或副詞的反義詞；②...enough to ...句式須用否定式；③too...to...結構有邏輯主語時,...enough to...結構也要加上邏輯主語.例如：
She is too young to do the work.→She isn't old enough to do the work.
2.將too...to...結構轉換為so...that...結構時要注意：①so...that...結構是復合句,so的后面接形容詞或副詞,that的后面接從句；②that后面的從句要用否定形式.例如：
She is too young to do the work.→She is so young that she can't do the work.