"What is your expertise?" is correct. "Expertise" means the complete collection of a person's special skills and as such agrees with singular verbs. A sentence with the same meaning but a plural verb would be "What are your expert skills?"
The phrase "Is you don't miss me do you" is not grammatically correct. It should be rephrased to something like "Don't you miss me?" to be correct.
Yes. You can also say "shows proficiency in"
This is not grammatically correct. The correct form is 'you do not know', or the abbreviated 'you don't know'.
Sure. It would also be grammatically correct to write He spoggled his nubbix on the goober. Grammatically correct and meaningful are not the same.
No, it is not grammatically correct. The correct way to say it is "your older sister."
The phrase "Is you don't miss me do you" is not grammatically correct. It should be rephrased to something like "Don't you miss me?" to be correct.
Yes. You can also say "shows proficiency in"
Yes, 'for free', is grammatically correct.
"Not like that" can be grammatically correct, depending on the context.
Yes! That is grammatically correct!
This is not grammatically correct. The correct form is 'you do not know', or the abbreviated 'you don't know'.
'What a drunkard you are' is a grammatically correct English sentence.
"That was wrong" is a grammatically correct sentence.
Yes, it is grammatically correct.
Yes, Almighty God is grammatically correct.
Sure. It would also be grammatically correct to write He spoggled his nubbix on the goober. Grammatically correct and meaningful are not the same.
No, it is not grammatically correct. The correct way to say it is "your older sister."