When, before, after
Today: three connectors that put a clock on a sentence. 時 (とき) means 'when' — clip a clause in front of it and you get 'when X (happens)'. 前 に (まえ に) means 'before' — and 後 で (あと で) means 'after'. The catch is the form of the verb that comes in front. Japanese plays a small but consistent trick: dictionary form before 時 and 前 に; past form (〜た) before 時 and 後 で — depending on what you mean. Once you see the pattern, it's the same logic every time.
The plain past — a quick rebuild
Today's patterns lean on the plain past form (also called the た-form). Good news: it's the て-form with one swap — て → た, で → だ. So たべて → たべた ('ate'), のんで → のんだ ('drank'), 行って → 行った ('went'), 見て → 見た ('saw'), した ('did'), 来た ('came'). Same as the polite 〜ました, just plain. We'll keep speaking in 〜ます at the end of full sentences; the plain past lives inside clauses, in front of words like 時.
〜時 — when X
時 (とき) is the noun 'time' acting as a connector. Stick a clause in front and it means 'when (that clause is true)'. The form of the verb tells you the timing. Dictionary form + 時 = 'when X happens / happens habitually': たべる 時、てを あらいます。 = 'When I eat, I wash my hands.' (every time, or just before the eating). Past form + 時 = 'when X had already happened': たべた 時、おいしかった です。 = 'When I ate (it), it was tasty.' The verb in front of 時 is plain — never 〜ます 時. Adjectives and nouns also slot in: さむい 時, しずか な 時, がくせい の 時 ('when I was a student').
〜前 に — before X
前 に ('mae ni') means 'before'. The verb in front is always dictionary form, no matter when the action actually happened. たべる 前 に、てを あらいます。 = 'Before eating, I wash my hands.' ねる 前 に、本 を よみました。 = 'Before going to bed, I read a book.' Yes — the main verb is past, but ねる stays in dictionary form. Think of it as 'before the eating-event,' not 'before I ate.' With a noun, drop に and use の 前 に: しごと の 前 に コーヒー を のみます。 = 'I drink coffee before work.'
〜後 で — after X
後 で ('ato de') means 'after'. The verb in front is always past form (〜た). たべた 後 で、コーヒー を のみます。 = 'After eating, I drink coffee.' しごと が おわった 後 で、ともだち と あいました。 = 'After work ended, I met a friend.' With a noun, use の 後 で: しごと の 後 で, じゅぎょう の 後 で. The pairing is symmetric and easy to remember: dictionary 前 に, past 後 で.
Why dictionary before, past after?
English uses 'before/after' with the same verb form, so this asymmetry is the single thing that trips learners up. The Japanese logic: 前 に anchors the event in the future of the clause it modifies — 'before this thing happens.' 後 で anchors it in the past — 'after this thing has happened.' Even when the whole sentence is set in the past, Japanese marks the internal timing of each piece. So ねる 前 に 本 を よみました stays plain dictionary ねる: at the moment of reading, the sleeping was still in the future. Don't fight it — read the rule once, do five examples, and it locks in.
Mixing it with adjectives and nouns
時 also works after い-adjectives, な-adjectives, and nouns. さむい 時、コート を きます。 = 'When it's cold, I wear a coat.' しずか な 時、本 を よみます。 = 'When it's quiet, I read.' こども の 時、にほん に いました。 = 'When I was a child, I was in Japan.' Note the noun + の + 時 shape — same の as 'X of Y'. For 前 に and 後 で, only verbs and nouns work: ごはん の 前 に, じゅぎょう の 後 で.
