都2、就2、还是1

或者 is the 'or' you use when you are telling, not asking. Say 我喝茶或者咖啡都行 and you are simply laying out options. The second it becomes a real question where someone must pick, Chinese reaches for 还是. So 你喝茶还是咖啡？ puts two cups on the table and waits for a choice. Picture 还是 as a fork in the road held up for the other person. 或者 is a buffet: take whatever, nobody owes you an answer. Choice questions have worked this way forever: “你喜欢看老电影还是新电影？” ── [《你喜欢看老电影吗？》](/read/do-you-like-old-movies#s1)

还是 questions are choice questions, not yes or no questions, so 是 has nothing to grab onto. Answer 你喜欢老电影还是新电影？ with 是 and the listener just waits for the rest of your sentence. Pick one side instead: 老电影, or 我喜欢老电影, or a lazy 老的. Tea or coffee? A flat 茶吧 does the whole job. If both are fine, 都行 or 两个都喜欢 kills the question cleanly. Repeating the full sentence back is grammatically legal but sounds like a nervous exam answer.

都 means every one of us, no exceptions — it scoops up the entire group. 也 means me too, on top of whoever else is already in. 我们都喜欢老电影 says all of us like them. 我也喜欢老电影 says I like them as well. When you genuinely need both, 也 comes first and 都 follows: 我们也都是学生. Flipping them to 都也 is never right. This is the same scooping job [都 does for 'all'](/grammar/dou1-all-62). In a group chat, 我们都去 means the whole crew is coming; 我也去 means you are tagging along.

就 always marks a small gap between what you expected and what actually happens. In 我就来 the gap is time: the wait will be tiny, so it reads as 'right away'. In 我就一百块 the gap is amount: fewer than you assumed, so it reads as 'only one hundred'. Same word, same job, different ruler. 他六点就来了 feels early and slightly impressive. 就剩两分钟了 feels tight and urgent. Compare 才, which marks a big, annoying gap: 他十点才来 means he rolled in way later than you wanted.