Yes. The classic example is for a student to punctuate: Where William had had had had, Charles had had had.
(Where William had had "had had", Charles had had "had")
and your stu stu stu stupid >:) ha ha ha ha ha ha ha ha
The word "looked" is a correctly used modifier in the sentence.
I think that the above sentence used in this term, is correctly used in this way.
In the sentence, It's up to you to decide, It's is used as a contraction for It is. It's used correctly here.
No, it is not used correctly. The correct way to use it is You are most welcome.
Yes; there are none.
The sentence "She quickly ran to the store to buy some groceries" contains a correctly used modifier in italic.
In the above sentence the word regarding is used correctly.
The sentence "I am going to the store, to buy some milk and bread, after work." uses commas correctly to separate two clauses in the sentence.
Correctly is the adverb in that sentence.
its welcome, not welcomed
He spoke sharply to his sister
Their house is over there; they're not home.