not +adj.+enough to do sth是不够。。。而不能做某事
too+adj.+to do sth.是太。。。以致不能做某事 ,其实两者可以互换!
例:He is not tall enough to catch the bird. =too short to catch the bird (他不够高去捉小鸟=他太矮以致不能捉小鸟)
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PS:如果adj.是willing(乐意)等意思的词语时,too+adj.+to do sth.意为肯定。如:He is too willing to help you.他很乐意去帮助你,而不是“他太乐意以致不能帮助你”
前者是不够怎样而做不了某事
后者是太怎样而做不了某事
example: not tall enough to do sth
=too short to do sth