到底 vs 终于

终于 lands the long-awaited result — "at last" (他终于完成了他的目标); 到底 presses for the bottom line and sharpens questions (到底是什么).

到底

dàodǐ ㄉㄠˋ ㄉㄧˇ

finally; in the end; when all is said and done

问题是她到底来还是不来。

The point is whether she will come or not.

终于終於

zhōngyú ㄓㄨㄥㄩˊ

at last; in the end; finally

他终于从房间里走了出来。

He came out of the room at last.

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