# 到底 (dàodǐ) vs 终于 (zhōngyú): "On Earth / After All" vs "Finally"

Source: https://sentencecoach.com/grammar/daodi-vs-zhongyu
Level: HSK 3–4

终于 means "finally / at long last" in statements, showing that a long-awaited (usually hoped-for) result has happened: 春天终于来了, 我终于写完作业了. 到底 is used in questions (A-not-A, 还是 or question words) to press for a final answer ("on earth / after all"): 你到底去不去？ "Are you going or not?!" Never use 终于 in a question, and never use 到底 with 吗.

Patterns:
- Subject + 终于 + Verb + 了: Statement: at long last achieved.
- Subject + 到底 + A-not-A / Question word？: Urgent question ("on earth / in the end"): 这到底是怎么回事？
- 到底 + 是 + Noun（statement）: "After all (as expected of…)": 到底是老手 "A veteran after all".

Examples:
- 经过三年的努力，她终于考上了理想的大学。 (jīng guò sān nián de nǔ lì, tā zhōng yú kǎo shàng le lǐ xiǎng de dà xué.) — After three years of hard work, she finally got into her dream university.
- 你到底想吃什么？快决定吧！ (nǐ dào dǐ xiǎng chī shén me? kuài jué dìng ba!) — What on earth do you want to eat? Decide quickly!
- 明天你到底去不去？给我一个准话。 (míng tiān nǐ dào dǐ qù bu qù? gěi wǒ yí gè zhǔn huà.) — Are you going tomorrow or not? Give me a definite answer.

Common mistakes:
- ✗ 你终于去不去？ → ✓ 你到底去不去？: Pressing for an answer in a question uses 到底; 终于 is for statements.
- ✗ 你到底知道吗？ → ✓ 你到底知不知道？ / 你到底知道什么？: 到底 questions use A-not-A (知不知道), 还是 or a question word, never simple 吗.

FAQ:
- Q: Can 到底 also mean "finally"?
  A: Yes, in statements, usually with 还是 or 了: 他到底还是来了 "He came in the end." 终于 is the everyday choice when a hoped-for result finally arrives.
- Q: What is the difference between 终于 and 最后 (zuìhòu)?
  A: 终于 carries a feeling of relief after waiting or trying hard (终于找到了); 最后 simply states the final item or what happened last in a neutral sequence (最后我们坐地铁回去了).