不定式的特殊句型too…to…

1）too…to太…以至于…

He is too excited to speak.

他太激动了，说不出话来。

----Can I help you?需要我帮忙吗?

----Well,I'm afraid the box is too heavy for you to carry it,but thank you all the same.不用了。这箱子太重，恐怕你搬不动。谢谢您。

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 late to mend.(谚语)

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。