It is correct as it stands. Also correct would be to add the understood verb at the end: You were not as comfortable as he was.
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In spoken English, "as him" is perfectly acceptable. In written, at least if not representing dialog, "as he was" is the best answer ("as he" is technically correct, but very stilted).
no_____If the sentence is You do do that (meaning You are in the habit of doing that) the grammar is perfectly correct and the sentence 'does have correct grammar'.
The correct grammar for this sentence is: "When did you send it?"
That sentence is grammatically correct.
The correct grammar is "Between you and me."
"Roger and I appreciate what you did" is correct grammar
The grammar in the question is correct.
Yes, that sentence is correct grammar.
No.
Yes, 'you were correct' is perfect grammar. An example sentence: You were correct when you said that a tomato is a fruit.
Yes, this sentence is correct grammar.
The sentence,'Its a cold sunday weather so wear your comfortable clothes' is not correct grammatically and should be rewritten to be 'It's a cold Sunday; so wear your comfortable clothes'.
Yes. What is not correct is your putting the article "a" before grammar.