不但

不但 (bùdàn) is a conjunction meaning 'not only,' the opening half of a correlative pair. It sets up a two-part sentence and almost always needs a second connector — 而且 (moreover), 还 (also/still), 也 (also), or 并且 — to complete the 'not only A but also B' idea: 他不但会说中文，而且会写 (he not only speaks Chinese but also writes it). The key rule English speakers must learn is placement relative to the subject: if both clauses share one subject, 不但 goes after it (他不但…); if the two clauses have different subjects, 不但 goes before the first subject (不但他会，我也会).

不但 cannot stand alone the way English 'not only' sometimes does — the second half is expected. It escalates from a smaller point to a bigger or more surprising one.