[時段] 沒 [動詞]grammar point · tier 2 · duration + negation (haven't done X for [duration])
Measures how long an action has been absent: the duration sits before the negated verb and counts the empty stretch, not the doing. Final 了 stretches the gap up to now.
You want to say how long it has been since something last happened — the gap, not the doing.
序 · The move
1name the length of the empty stretch and place it firstis the duration measuring a gap (nothing happened), not a span of doing? a span of doing goes after the verb (睡了兩天)
2set 沒 before the verb to sink the actionis it 沒 (the action did not occur), not 不 (unwilling / habitually not)?
3add 了 at the end if the gap is still openthe 了 here stretches the gap to now; do not put 了 directly on the 沒-verb (✗ 沒睡了覺)
例 · Examples
1他兩天two days (the length of the gap)沒not (sinks the verb — it didn't happen)睡覺sleep了and it still holds now，讓他多睡一點。
He hasn't slept for two days; let him sleep a bit more.
Affirmative duration puts the span AFTER the verb — 睡了兩天 (slept for two days, doing it). Negated duration puts the span BEFORE 沒 — 兩天沒睡 (two days with no sleep, the gap). Front = the stretch was empty; back = the stretch was filled.
沒 sinks an action that did not occur over the stretch; 不 bars will or habit. 兩天沒睡 (two days without sleep, factual gap) vs 不睡 (won't sleep / refuses).
duration after the negated verb: 他沒睡覺兩天 → 他兩天沒睡覺 (the gap-length goes before 沒)
negating with 不: 他兩天不睡覺了 → 他兩天沒睡覺了 (a factual unslept gap takes 沒, not 不)
stacking 了 on the 沒-verb: 他兩天沒睡了覺 → 他兩天沒睡覺了 (沒 already denies it; 了 sits sentence-final to carry the gap to now)
English says 'hasn't slept for two days' with the duration trailing at the end; learners copy that order and put 兩天 after the verb, but a negated Chinese duration must be fronted before 沒.