Sentences corretions

could anybody correct the sentences below for me?

Please tell me if any of them can't be used in formal writing.

Great Thanks In advance

ex.My mother is a wet blanket, as she always make a lot of excuses to stop us from going for a trip.

ex."You can solve this question by one only a method. ""As a saying goes: All roads lead to Rome."My teacher said.

ex.A man becomes learned by asking questions.So if you want to get a good result, You must ask your teacher when you face a problem.

ex.John:Yoga is very difficult.

Mary:All things are difficult before they are easy.

ex.He always be together with those poor boys. I think this why we say birds of a feather flocks together.

ex.I think computers are perfect. Remember that every advantage has its disvantage.

ex.He is always laughing at my failure in this exam. So I told him that every day is not Sunday.

ex.My mind is not good. However,I think I will get a good result,if I try my best to study.As I believe that constant dripping wears away a stone.

ex.John:"Unbeliveably,it's nine already."

Mary:"Happiness takes no account of time."

ex.The hunter set a trap to catch the swine.But finally he was caught by the trap set by himself.Harm set,harm get.