1. He loves to eat onion soup (by the way in English do we say to eat soup or to drink it ? Because soup is something liquid, not solid to eat.). 

Hmm. I certainly don't say "drink soup" but now that you mention it, "eat soup" is odd too. I would say simply "He loves onion soup." (I certainly like the kind with melted cheese on top!)

2) We went to the show even though we hadn't been invited.

This is fine.

3)He has hardly any dollars money in his pocket to buy food.

4) It's better to wait (or) it's better wait ?    

1) If you held a knife to my throad and said "Choose! Eat soup or drink soup?" then I would choose "eat." But it doesn't sound natural to me. He loves to have soup as an appetizer. He loves soup as his main course.

2) He has only a few dollars in his pocket. He has hardly any money.

I can't see the original post as I write this reply, so perhaps I gave you bad advice earlier. "He has few dollars" isn't idiomatic. He has only a few dollars or he has little money. Likewise, "He has hardly any dollars" simply isn't idiomatic.

You can use it for other nouns: He has many toys, he has a few toys, he has few toys, he has hardly any toys.

Just not dollars, because that means "money," a non-countable noun. If you want to refer to single dollar bills (for example, you need them to tip the waiter, the valet, the doorman, etc.) then you can say "He'll have a hard time tipping them all tonight - he has hardly any dollar bills on him."

Anonymous wrote:

Hi, Grammar Geek! - He has few dollars in his pocket to buy food.  ('Few' means 'not many'. Therefore, your sentence means 'He has not many dollars ... '   Hence, the sentence is not correct. He has a few dollars in his pocket to buy food. ( The sentence is correct if 'a' is added. )