水滴石穿 vs 亡羊补牢: Which Chengyu Fits?

How to decide

1. Reach for 水滴石穿 when the sentence points to steady effort can wear through stone. Its tone is positive, and the safest first test is whether the context resembles language learning, research, practice.
2. Bring in 亡羊补牢 when the sentence points to to repair the pen after losing sheep; better late than never. Its tone is corrective and practical, and the strongest clue usually looks closer to process correction, student advice, workplace safety.
3. The shared ground is narrow: both appear in effort and learning situations. The difference is not the Chinese topic label but the job each phrase performs in a sentence.
4. A safe English first pass is constant dripping wears away stone for 水滴石穿 and better late than never for 亡羊补牢, then check whether the surrounding sentence needs praise, warning, correction, or neutral description.

Wrong choice checks

• 水滴石穿: Do not use it for a one-time intense push; the idiom is about repetition.
• 亡羊补牢: Do not use it before any loss has happened. Use 未雨绸缪 for preparation in advance.
• Do not let the story image do all the work. Check what the speaker is judging before you pick either phrase.
• Do not swap the two phrases just because they share a theme. A nearby topic can still carry the wrong social judgment.

Where this comparison comes from

• Both phrases have full dictionary entries with examples, source notes, and usage boundaries.
• The comparison uses entry-level source references instead of adding new historical claims on the compare page.
• The page exists because learners often need to reject a near phrase, not only recognize a single chengyu.

• 水滴石穿: CC-CEDICT dictionary cross-check via MDBG
  Used to cross-check the modern headword, pinyin, and broad dictionary sense for 水滴石穿; this is not treated as the story source.
• 水滴石穿: Wiktionary open lexical reference
  Used as an open lexical reference for English readers checking the headword and common translation range for 水滴石穿; usage decisions still come from examples on this page.
• 水滴石穿: Chinese Text Project dictionary locator
  Used as a classical-text locator and Chinese reference cross-check for 水滴石穿; the entry still rewrites the learner explanation in this site's own order.
• 亡羊补牢: Strategies of the Warring States story tradition
  Use this as the broad Warring States anecdote locator for the lost-sheep repair story; the entry keeps the retelling concise for learners.
• 亡羊补牢: CC-CEDICT dictionary cross-check via MDBG
  Used to cross-check the modern headword, pinyin, and broad dictionary sense for 亡羊补牢; this is not treated as the story source.
• 亡羊补牢: Wiktionary open lexical reference
  Used as an open lexical reference for English readers checking the headword and common translation range for 亡羊补牢; usage decisions still come from examples on this page.
• 亡羊补牢: Chinese Text Project dictionary locator
  Used as a classical-text locator and Chinese reference cross-check for 亡羊补牢; the entry still rewrites the learner explanation in this site's own order.

Visual memory: The board keeps both phrases visible at once so the learner decides by tone, context, and mistake boundary.