My friend just told me that his teacher, a native speaker, taught him - that many and much are mainly used in negative sentences and not commonly in affirmative sentences; furthermore, I happened to read an article concerning that matter while searching about it. Here are the examples the article gives:
There aren't many chairs in the room.
I don't have much time.
He doesn't need much money.
As this is not familiar with me, I am rather confused about this. I have never thought that many is not common in affrimative sentences, and because of that I got a question: what adjective should I use then in formal affirmative sentences? I know that a lot of is informal and so is not preferable to use it in formal contexts. For example, what should replace many in the following sentence? And is many that not suitable to be used in affirmative sentences?
He has many questions I could not possibly answer.