倉庫の鍵を掛け忘れたのはいったい誰ですか。

storehouse; warehouse; godown

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

key; lock

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to hang (e.g. picture); to hoist (e.g. sail); to raise (e.g. flag); to sit; to take (time, money); to expend (money, time, etc.); to make (a call); to multiply; to secure (e.g. lock); to put on (glasses, etc.); to cover; to burden someone; to apply (insurance); to turn on (an engine, etc.); to set (a dial, an alarm clock, etc.); to put an effect (spell, anaesthetic, etc.) on; to hold an emotion for (pity, hope, etc.); to bind; to pour (or sprinkle, spray, etc.) onto; to argue (in court); to deliberate (in a meeting); to present (e.g. idea to a conference, etc.); to increase further; to catch (in a trap, etc.); to set atop; to erect (a makeshift building); to hold (a play, festival, etc.); to wager; to bet; to risk; to stake; to gamble; to be partway doing ...; to begin (but not complete) ...; to be about to ...; indicates (verb) is being directed to (someone)

to forget; to leave carelessly; to be forgetful of; to forget about; to forget (an article)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

...the heck (e.g. "what the heck?"); ...in the world (e.g. "why in the world?"); ...on earth (e.g. "who on earth?"); one object; one body; unity; one form; one style; one Buddhist image (or carving, etc.); generally; in general

who

be; is

indicates a question (sometimes rhetorical); or; whether or not; some- (e.g. something, someone); indicates doubt, uncertainty, etc.; emphatic prefix; suffix forming adjectives or adverbs; in that way