Questions (interrogatives) in Quenya can be indicated by intonation alone, just like in English: túlalye? “you are coming?” However, more often they are marked with the interrogative particle ma. This particle was derived from the ancient root √MA, which was mentioned in several places (PE17/68, 162; VT47/19). Tolkien discussed its use in some detail in Late Notes on Verb Structure (LVS) from 1969:

Here is the full entry on negation. The “Conceptual Development” section is largely unchanged except for minor edits. I added a “Neo-Quenya” section exploring its possible use in practice.

I’m posting the first half of this entry for purposes of discussion, because I’m very much on the on fence about how to address Neo-Quenya.

The subjunctive mood is used for various “unreal” (conditional or hypothetical) statements: things where the speaker is uncertain whether or not they are true. These are slightly different from the optative (things the speaker hopes or wishes were true) and the imperative (actions the speaker demands be done).

An optative is the expression of a wish, and Quenya usually formulates such expressions using the adverb nai “may it be that, be it that, maybe”. Its most famous use is in nai hiruvalye Valimar, nai elye hiruva “maybe thou shalt find Valimar, maybe even thou shalt find it” in the Namárië poem (LotR/378). Tolkien described this formulation in several places: