A comma would typically go after "for instance" because you're about to give an example of something. You will frequently find a comma where you take a breath in that sentence.
No, a comma before "as appropriate" is not necessary. It depends on the context of the sentence and whether it flows better with or without the comma.
Not at the beginning of a sentence. As you know is a clausal sentence adverbial, and as such it should generally be set off by punctuation. That would mean a comma after it at the beginning of a sentence, a comma in front of it at the end of a sentence and commas on both ends when it appears in the middle of a sentence: "He is, as you know, rather obstinate."
no . Additional: 'Which' sometimes has a comma before it, but it depends on the sentence. I find it hard to imagine a situation when 'which' would have a comma after it.
It is usually appropriate to place a comma before "but." One should not use a comma after "but."
Quotation marks typically go before or after commas, depending on whether the comma is part of the quoted material. If the comma is part of the quoted material, it goes inside the quotation marks. If the comma is not part of the quoted material, it goes outside the quotation marks.
Yes
No, a comma before "as appropriate" is not necessary. It depends on the context of the sentence and whether it flows better with or without the comma.
Sometimes, but not always. There is no one single rule that applies to "but." ----
Not at the beginning of a sentence. As you know is a clausal sentence adverbial, and as such it should generally be set off by punctuation. That would mean a comma after it at the beginning of a sentence, a comma in front of it at the end of a sentence and commas on both ends when it appears in the middle of a sentence: "He is, as you know, rather obstinate."
No
It depends on the type of sentence. So your answer would be not all the time. I hope that helps! :)
A period should come before the footnote at the end of a sentence, while a comma should not.
No, definitely not. In very many cases it would not even be optional. It would simply be wrong.
If a comma is needed, it normally comes after parenthesis.
The comma would come after it.
no . Additional: 'Which' sometimes has a comma before it, but it depends on the sentence. I find it hard to imagine a situation when 'which' would have a comma after it.
Return to sender does not require quotation marks or a comma.