Expressing "when" with "dengdao"
The word 等到 (děngdào) can trip up learners, because while it can literally mean "to wait until," it also has the less literal translation meaning "when (the time comes)" or "by the time (something happens)." This is a pattern that appears in complex sentences, with 等到 acting as a conjunction and appearing in the first part as the first word in the sentence.
Used for the Future
When talking about the future, the second part of the sentence uses 就 (jiù) or 再 (zài).
等(到) + Time / Event ，Subj. + 再 / 就 + Predicate
The predicate part of the pattern can be a verb or an adjective.
- 等到 老板 知道 就 麻烦 了。When the boss finds out, we'll be in trouble.
- 等 雨 停 了 我 再 出门 。When the rain stops, I'll go outside.
- 等到 秋天 ，这些 树叶 就 会 变 黄 。When autumn arrives, these leaves will turn yellow.
- 等 做 完 这个 项目 ，我 就 休假 。I will take a vacation when I finish this project.
- 等到 老板 签 了 字 ，我 再 做 安排 。I will make arrangements once the boss signs off on it.
Used for the Past
For the past, the second part of the sentence uses 才 (cái). This pattern is very similar to how 直到 (zhídào) is used to mean "all the way until", and also overlaps with the use of 才 to express lateness.
等(到) + Time / Event ，Subj. + 才 + Predicate
- 等 我 回 了 家 ，才 发现 手机 忘 在 了 出租车 上 。I didn't realize I left my cell phone in the taxi until I got home.
- 等到 孩子 上 了 小学 ，她 才 开始 工作 。She didn't start working until her children had started elementary school.
- 等 学生 都 安静 了 ，老师 才 开始 上课 。The teacher didn't begin the class until the students all became quiet.
- 等 他 有 了 孩子 ，才 知道 做 父母 多么 不 容易 。It wasn't until he had had a child that he realized how hard it is to be a parent.
- 等到 他 到 家 了 ，才 发现 他 没有 带 钥匙 。It wasn't until he got home that he found that he didn't have his keys.
Sources and further reading