I think I would take it as defining too, and thus omit the commas in the extended version: 1. Distributive justice which is absolute, rigid, and unvarying must be observed by anyone who... MrP

Hello Renan, I hear "lonely" too. It may be that some other version of the song has "younger", though. Best wishes, MrP

Hello Non, welcome to English Forums! Would this be for a test or essay of some kind? (Unfortunately we wouldn't be able to give answers for tests or essays; though if you wanted to put down your thoughts, we'll look at them for you.)

If the original examples are grammatically objectionable, then so is e.g. 1. Whose mother abandoned him when he was two years old? — which would be bad news for quizmasters. MrP

Not the second version, Anon. All the best, MrP

(Strictly speaking, Anon, "singularia tantum" is the plural; the singular is "singulare tantum".)

Grammatically, I think it can only be "correct", since "forever" can be a noun, as in: 1. It took me forever . (Cf. "It took me an hour ".) Semantically, you might say that it's not quite right; but presumably that slight

Hello Anon, 1. I haven't seen you in forever. I would take this as a jocular variant of: 2. I haven't seen you in an age . For "an age", which is already hyperbolic, the speaker substitutes "forever", which piles hyperbole

There is some variation; the Times and the Oxford University Press set film titles in italic. Some might use underlining where italics aren't available, e.g. in handwritten texts. MrP

I would opt for "delivers", Anon; here "pair" is the subject of the verb. All the best, MrP