Yes.
Why did you left is grammatically incorrect. It should be: Why did you leave? Why did she leave? Why did he leave? Why did they leave?
No, not even close. What exactly are you trying to ask?
Yes, the phrase "I should be grateful if you would" is grammatically correct. It is a polite way to ask someone to do something for you.
The grammatically correct version is Do you feel any aches in any places in your body?
No, "hows you" is not grammatically correct. "How are you?" is correct.
This sentence is grammatically correct. However, it would be more correct to say, "I want you to pierce my baby's ear (or ears)."
I would say "beaten".
Your question wasn't even grammatically correct enough for me to understand what you were asking.
Yes it is. The sentence "This will be an exciting month for me" is absolutely correct (it needs a period at the end, of course). But "a correct grammar" is not-- you want to ask whether it is "grammatically correct," or to be simpler, ask whether it is "good English."
Yes, "By whom was this written?" is a correct question. It is the formal and grammatically accurate way to ask about the authorship of a written work.
est-ce que c'est correct ? (common and grammatically correct)est-ce correct ? (a bit 'upper-crust').
No. Weather is not countable, so therefore you would not use "much". How is the weather? Oh, it's pretty cold out today!