1. “too+形容词或副词+to+动词原形”，其基本意思是“太…而不能…” 例如：
  He is too young to know right from wrong. 他太小，还分不清是非。
  He is too shy to speak to her. 他太害羞，不敢同她讲话。
  It’s too cheap to be good. 这东西太便宜，好不了(即便宜无好货)。
  He is too young to know right from wrong. 他太小，还分不清是非。
  有时不定式前可以带有一个由介词for引出的逻辑主语：
  The maths problem is too difficult for me to work out.这道数学题太难我解不出来。
  The box is too heavy for me to carry. 这个箱子太重，我提不起。
  另外，该句型有时可与so [such]…that结构转换：
  The box is too heavy for me to carry.
  →The box is so heavy that I can’t carry it.
  →It is such a heavy box that I can’t carry it.

2. 如在too前有否定词，则整个句子用否定词表达肯定，too 后那个词表达一种委婉含义，意 为"不太"。
  It’s never too old to learn.活到老，学到老。（要学永远都不迟。）
  It’s not too late to mend.亡羊补牢，永不为迟。（改过不嫌晚）

3. 当too 前面有only, all, but时，意思是：非常… 等于very。
  I'm only too pleased to be able to help you. 我非常高兴能帮助你。
  He was but too eager to get home. 他非常想回家。