但、但是、那、虽然、还是2、因为2、所以

English teachers drill you never to say 'although...but' or 'because...so' in one sentence. Chinese does the opposite: the pair is the normal, complete shape. Cut the second half and the sentence goes limp, like a joke with no punchline. 虽然 alone is allowed, but in most conversations it sounds unfinished. 因为...所以 works the same way, except fast speech often drops 所以 and keeps 因为. Here is the pair doing its job in real text: “因为我不喜欢运动，所以这两个我都不喜欢。” ── [《你喜欢看老电影吗？》](/read/do-you-like-old-movies#s9)

但 and 但是 carry identical meaning, full stop. The difference is rhythm: 但 is one beat, so it slides into texts, quick opinions, and fast talk. 但是 takes more room to say, which makes the contrast land heavier. Both are fine in speech, and tight writing leans on 但. One rule never bends: these words only open the second half, never the first. Also skip the dramatic pause — 但，我不去 sounds like a movie trailer.

那 at the start of a reply means 'then', 'so', or 'in that case', and it pushes the conversation forward. Textbooks push 那么, which is correct but stiff for WeChat and daily chat. 然后 is a different animal: it marks a step in a sequence, not a reaction. Reach for 那 whenever you are responding to what someone just said: 那算了, 那走吧, 那我请客. It also still means 'that' in front of a noun, so watch the comma.

还是 turns a sentence into an open pick: A or B, you choose. Yes/no questions take 吗, so 是 and 不是 simply have nothing to attach to here. If both options are fine, 都行 or 随便 rescues you instantly. The same shape works with verbs: 你去还是不去？gets answered with 去 or 不去. In plain statements about options, English 'or' switches to 或者, so keep 还是 for questions.