目を覚ましてみるといっさいが夢であることが分かった。

eye; eyeball; eyesight; sight; vision; look; stare; glance; an experience; viewpoint; stitch; texture; weave; ordinal number suffix; somewhat; -ish

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 awaken; to disabuse; to sober up; to dampen; to throw a damper on; to spoil

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

once or twice; repeatedly

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

dream

be; is; indicates past or completed action; indicates light imperative

a certain ...; some ...

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

to understand; to comprehend; to grasp; to see; to get; to follow; to become clear; to be known; to be discovered; to be realized; to be realised; to be found out