ドアに鍵がかかっていることを確かめましたか。

door (Western-style)

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

key; lock

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to take (a resource, e.g. time or money); to hang; to come into view; to arrive; to come under (a contract, a tax); to start (engines, motors); to attend; to deal with; to handle; to have started to; to be on the verge of; to overlap (e.g. information in a manual); to cover; to (come) at; to be fastened; to be covered (e.g. with dust, a table-cloth, etc.); to be caught in; to get a call; to depend on

thing; matter; incident; occurrence; event; something serious; trouble; crisis; circumstances; situation; state of affairs; work; business; affair; after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to; nominalizing suffix; pretending to ...; playing make-believe ...; alias; aka; nickname; alternative name; also known as

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 ascertain; to check; to make sure

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