①too后接表示主语态度、情感、心情或倾向的词时表示肯定。常见的有glad、eager、anxious、happy、pleased等。
We are too eager to know the result.
②too...to结构与not/never等否定词连用时表示肯定。
Physics isn't too difficult to learn.
③在too...to结构中,too前有only/just/all/but等词也表示肯定。
I'm only too glad to meet you here.
You cannot be too careful to cross the street.