grammar → 還
TSUMUGU · TBCL 4 (est.) · 語法
還 grammar point · tier 1 · additive 還 (and on top of that, also does …)
· hái
Marks a further activity the same subject takes on in addition to what was just stated — and on top of that, also does B.

Hook inherited from 比…還….

Marks a further activity the same subject takes on in addition to what was just stated — and on top of that, also does B
框 · Frame
[subj] [activity A], 還 [activity B]
觸 · Trigger
The same subject is already doing one thing, and a second activity is piled on top.
序 · The move
1State the first activity, then keep the same subject for the second.Same person doing both? A fresh subject in the second half wants 而且, not 還.
2Head the second predicate with 還, before its verb.Does B pile onto A, or replace it? If A is dropped for B, this is not the additive 還.
3Leave the first activity standing; the second is an extra load, not a swap.Both activities still true at once? 還 stacks; it never trades one out.
例 · Examples
1他白天during the day上班go to work，晚上in the evening還on top of that, also當家教work as a tutor，根本沒時間have no time at all回信answer letters。
He works during the day and, on top of that, tutors in the evening, so he has no time at all to answer letters.
界 · Boundary
也
也 lines a second item up as the same kind, flat alongside the first (he too / likewise). 還 piles the second on as an extra load, stressing there is more on top. Level equivalence vs added weight.
再
再 repeats or continues the same action a further time (do it again). 還 adds a different, second activity. Same act once more vs a new act stacked on.
不但…還…
The 不但…還… frame opens the count with 不但 (not only) and needs both halves. Additive 還 here stands alone in the second clause without 不但 leading the first.
他白天上班，晚上再當家教。 (再 = repeat the same act) → 他白天上班，晚上還當家教。 (還 adds a different second activity)
他白天上班，而且他太太晚上還當家教。 (new subject under 還) → 他白天上班，晚上還當家教。 (keep one subject for additive 還; a new subject takes 而且)
他不工作，晚上還當家教。 (first activity cancelled, nothing for 還 to stack on) → 他白天上班，晚上還當家教。 (the first activity must stand for 還 to add to it)
English 'also' or 'too' often drops to the end of the clause; Chinese 還 sits up front, right before the second verb, and signals an extra load rather than flat equivalence.
關 · Related
不但還也the framed version: 不但 opens the count, 還 heads the added second clause — this is that 還 standing alone連…都…neighbouring escalation — pushes to the extreme case rather than stacking a further activity因為…所以…another way two clauses join, cause→effect rather than addition