I have two questions that have made me confused since yesterday.
a) Is it possible to use "so+adjective+to-infinitive" form instead of using "so+adjective+as+to-infinitive"? Is it possible to make the meaning remain the same?
b) I saw this explanation in the internet says "This structure(too + adjective + to- infintive) is used to explain why someone can’t do something". But in my example(the fourth sentence), the sentence isn't explain why she can't do something. The sentence explainig why she can do but the thing she do is too idiotic.
1-She is so stupid that she believed his so-called claims
2-She is so stupid as to believe his so-called claims
3-She is so stupid to believe his so-called claims
4-She is too stupid to believe his so-called claims.