grammar → 竟
TSUMUGU · TBCL 5 (est.) · 語法
grammar point · tier 1 · adverbial 竟 (against all expectation)
· jìng
Adverb before the verb that flags the outcome as running against expectation.

字源 FORM what the parts do

A tune (音) over a standing figure (儿): the piece runs to its last note, the figure present through it to the end. The end is where 竟 leaves its charge — the surprise lands on whatever the final note turns out to be.

故事 STORY a scene to remember it by

The music plays out to its final note, and the figure standing through it finds the wrong note waiting where the right one was due.
字源記憶法自撰
框 · Frame
[setup, often a stretch of time/effort] ,[subj] 竟 [verb + outcome]
觸 · Trigger
The end of a stretch lands on an outcome no one would have bet on, and you flag the jolt.
序 · The move
1Lay down the setup — a span of time, an effort, a state of affairs that sets an expectation.Is there an expectation in place for the outcome to violate?
2Drop 竟 directly before the verb of the surprising outcome.Does 竟 sit before the verb, not at the head of the clause like 居然 can?
3State the outcome that overturns the setup.Would a listener react with disbelief? If the result is merely awaited, not jolting, 竟 is wrong — reach for 終於.
例 · Examples
1短短short, brief不到less than幾年a few years的時間,這間公司的資本額capital amountagainst all expectation高達reach as high as數億several hundred million美金US dollars
In a span of barely a few years, this company's capital reached as high as several hundred million US dollars.
界 · Boundary
居然
竟 sits tight before the verb and reads formal/written; 居然 carries the same surprise but moves freely to the clause head and reads colloquial. 竟然 is 竟 loosened into the spoken register.
終於
竟 marks the outcome as contrary to expectation; 終於 marks an outcome that was awaited and finally arrived. Same finish line, opposite reaction — shock versus relief.
✗ 我等了三個小時,他竟到了。→ ✓ 我等了三個小時,他終於到了。(an awaited arrival is relief, not shock — use 終於)
✗ 竟這間公司倒了。→ ✓ 這間公司竟倒了。(竟 sits before the verb, not at the clause head)
✗ 他很努力,竟成功了,這是應該的。→ ✓ 他很努力,所以成功了,這是應該的。(an expected, deserved result cancels the surprise 竟 requires)
English 'actually' and 'in the end' both translate 竟, so learners reach for it whenever they say 'finally' — but 竟 fires only on a violated expectation, never on a result that was simply due.