In many West-European languages, the word or expression to mark polite requests ("please", "bitte", "s'il vous plaît") can be used with or without an (additional) verb (usually in imperative).
The latter (without an additional verb) is commonly used when replying to questions of offer or when ordering at restaurants:
Host: What would you like to drink?
Guest: A glass of water, please.
Gastgeber: Was willst du trinken? / Was wollen Sie trinken?
Gast: Ein Glas Wasser, bitte.
At a bar (with or without having been promted to order):
A beer, please!
Bitte ein Bit!
(The latter being the advert slogan of beer brand "Bitburger".)
These polite-request markers are usually translated to Esperanto as "bonvolu", which already is imperative and used like a auxiliary verb, i.e. requiring another verb (the one that would be in imperative in English, German or French) in infinitive.
Bonvolu doni al mi glason da akvo.
In the reply / restaurant order scenario this seems both overly long and somewhat awkward. (Is it?) What would be used in these situation in Esperanto? Can "bonvolu" be used without another verb? Maybe in another form, e.g. "bonvole" (adverbial) or "bonvolata" (participle of present) / "bonvolota" (participle of future)?