@ziawj2,
Quote:#9 through 11 are not [-] used very commonly in English, aren't [-] they?
When using normal neutral tag questions, Ziawj, a negative statement has a positive tag attached and a positive statement has a negative tag attached.
You have two negatives above. Yours should be,
#9 through 11 are
not used very commonly in English,
are [+] they?
As to the substance of your question, you are right, but that's only because very formal situations/highly deferential situations are not all that common.