too…to…结构一般表示“太…结果不能”,如：He is too weak to do the work.
注意：
too之前如果有only, only too 表“非常”、“很”意,此时不定式不再表否定意,而表肯定意.
如：They are only too lucky to go abroad for a visit. 他们很幸运去国外访问.
另外,too后如果是happy, glad之类形容词时,不定式也表肯定意,
如：She was too happy to meet her old friend in the street.
追加一个,Can’t...too...表示 “再...也不为过”“越...越好”
You can't be too careful when crossing the road.