莫非: Tentative Conjecture in Chinese
莫非
莫非 introduces a tentative conjecture, often with surprise, doubt, or a rhetorical shade: could it be that...? It normally scopes over the following clause and may be reinforced by sentence-final 不成. Its use leans formal or literary, but 莫非...吗 and 莫非...吧 are also attested and must not be rejected automatically.
Published July 16, 2026
Reviewed July 16, 2026
01 / PATTERN
See the Structure
MODEL
莫非 + Subject + Predicate (+ 不成)?
Read the structure
莫非 introduces a tentative conjecture, often with surprise, doubt, or a rhetorical shade: could it be that...? It normally scopes over the following clause and may be reinforced by sentence-final 不成. Its use leans formal or literary, but 莫非...吗 and 莫非...吧 are also attested and must not be rejected automatically. Keep the model 莫非 + Subject + Predicate (+ 不成)? visible while you compare each sentence.
他今天一直没来，莫非生病了？
He has not come in all day; could he be ill?
Choose the right context
To infer a possible explanation from an unexpected sign: 他今天一直没来，莫非生病了？ To voice a surprised or doubtful conjecture: 门怎么开着，莫非有人进去过？ With sentence-final 不成 when a stronger rhetorical or incredulous tone is intended: 莫非他忘了时间不成？
门怎么开着，莫非有人进去过？
Why is the door open? Could someone have gone in?
Respect the boundary
For a neutral request for unknown information; 莫非 normally carries the speaker's conjecture, surprise, doubt, or rhetorical stance. Do not require sentence-final 不成. It can reinforce the question, but a complete 莫非 clause can stand without it. Do not automatically reject 莫非...吗 or 莫非...吧. Both have attested uses, and the acceptability of particular combinations depends on the intended question and register.
他今天没来，莫非了生病？
(He did not come today; could he be ill?)
Repair the pattern
The particle 了 is placed directly after 莫非: 莫非 scopes over the proposition 生病了. The particle 了 belongs after the predicate and cannot be inserted between the conjectural adverb and that predicate. Sentence-final 不成 is stacked after 莫非: In the paired rhetorical form, 莫非 introduces the conjectured clause and 不成 closes it. Placing 不成 immediately after 莫非 breaks the frame.
他今天没来，莫非生病了？
Use the repaired structure without changing the intended meaning.
02 / MAP
Read the Sentence
Read from left to right and notice the job performed by each part. The labels describe this example; they are not a rule that every Chinese sentence must copy.
他今天一直没来，莫非生病了？
He has not come in all day; could he be ill?
他
莫非
This part occupies the 莫非 position in the model pattern.
今天
Subject
This part occupies the Subject position in the model pattern.
一直
Predicate (
This part occupies the Predicate ( position in the model pattern.
没
不成)?
This part occupies the 不成)? position in the model pattern.
来
莫非
This part occupies the 莫非 position in the model pattern.
，
Subject
This part occupies the Subject position in the model pattern.
莫非
Predicate (
This part occupies the Predicate ( position in the model pattern.
生病
不成)?
This part occupies the 不成)? position in the model pattern.
了
莫非
This part occupies the 莫非 position in the model pattern.
03 / EXAMPLES
Examples You Can Reuse
Keep the structure stable while changing the people, objects, times, or conditions. Pinyin is shown as reading support; use the Chinese sentence and translation to confirm the grammar relationship.
他今天一直没来，莫非生病了？
He has not come in all day; could he be ill?
门怎么开着，莫非有人进去过？
Why is the door open? Could someone have gone in?
你一直不说话，莫非不同意这个方案？
You have been silent; could it be that you disagree with this plan?
莫非我记错了日期？
Could it be that I remembered the date incorrectly?
他这么晚还没回来，莫非忘了时间不成？
He still has not returned this late; could he have forgotten the time?
你平时不认真学习，莫非要等到期末考试了才开始紧张吗？
Are you really going to wait until the final exam before you start worrying?
04 / LIMITS
When to Use It — and When Not To
Use it when
- To infer a possible explanation from an unexpected sign: 他今天一直没来，莫非生病了？
- To voice a surprised or doubtful conjecture: 门怎么开着，莫非有人进去过？
- With sentence-final 不成 when a stronger rhetorical or incredulous tone is intended: 莫非他忘了时间不成？
Do not use it when
- For a neutral request for unknown information; 莫非 normally carries the speaker's conjecture, surprise, doubt, or rhetorical stance.
- Do not require sentence-final 不成. It can reinforce the question, but a complete 莫非 clause can stand without it.
- Do not automatically reject 莫非...吗 or 莫非...吧. Both have attested uses, and the acceptability of particular combinations depends on the intended question and register.
05 / REPAIR
Compare Right and Wrong
Compare the smallest meaningful change. Each explanation identifies a placement, scope, form, or clause relationship instead of treating the whole sentence as one undifferentiated mistake.
他今天没来，莫非了生病？
他今天没来，莫非生病了？
The particle 了 is placed directly after 莫非
莫非 scopes over the proposition 生病了. The particle 了 belongs after the predicate and cannot be inserted between the conjectural adverb and that predicate.
门一直开着，莫非不成有人进去过？
门一直开着，莫非有人进去过不成？
Sentence-final 不成 is stacked after 莫非
In the paired rhetorical form, 莫非 introduces the conjectured clause and 不成 closes it. Placing 不成 immediately after 莫非 breaks the frame.
他今天没来，莫非了生病？
Put 了 after the predicate, not after 莫非: 他今天没来，莫非生病了？
门一直开着，莫非不成有人进去过？
In the paired form, move 不成 to the end: 莫非有人进去过不成？
06 / PRACTICE
Practice the Grammar Point
Complete three short tasks in order: judge the pattern, repair a common error, and build the sentence. Feedback is fixed and reviewed, so these activities do not use a checker allowance.
1. Judge the sentence
2. Choose the correction
3. Build the sentence
Build a complete sentence with 莫非.
07 / APPLY
Apply It in Your Sentence
Write one original sentence with 莫非. Your draft moves to the checker through this browser session, selects this grammar point as the first review focus, and waits for you to submit.
08 / QUESTIONS
莫非: Tentative Conjecture Questions
What does 莫非 mean in Chinese?
It introduces a conjecture colored by doubt, surprise, or a rhetorical stance, similar to 'could it be that...?' It often responds to evidence that the speaker finds unexpected.
What is the difference between 莫非 and 难道?
They overlap in doubtful or rhetorical questions. 莫非 often leans toward tentative inference and more formal or literary expression, while 难道 more readily carries challenge or rebuttal; this is a tendency, not a universal split.
Can 莫非 be used with 吗 or 吧?
Yes, both combinations are attested, although their distribution and tone vary. Do not reject a sentence solely because 吗 or 吧 appears; evaluate its word order, intended question, and register.
Must 莫非 be followed by 不成?
No. 不成 can close and strengthen a rhetorical question, but 莫非 may introduce a complete conjectural question by itself: 莫非我记错了日期？
09 / SOURCES
Sources and Review Notes
These references support different parts of the lesson. GF0025-2021 supports level placement only; professional grammar works support the explanation, limits, examples, and cross-checks. Their inclusion does not imply endorsement.
Modern Mandarin Chinese Grammar: A Practical Guide, 3rd ed.
Ross, Ma, Chen, He and Yeh · Routledge · 2024
Locator: Construction index and function chapters relevant to 莫非
Supports the learner-facing account of where 莫非 appears and what communicative job it performs.
Official sourceChinese: A Comprehensive Grammar, 2nd ed.
Yip and Rimmington · Routledge · 2016
Locator: Relevant sentence and clause chapters for 莫非
Cross-checks the 莫非 + Subject + Predicate (+ 不成)? pattern, clause relationship, and limits represented by the reviewed examples.
Official sourceChinese Proficiency Grading Standards for International Chinese Language Education (GF0025-2021)
Ministry of Education and State Language Commission · Ministry of Education of the PRC · 2021
Locator: Appendix A, combined Levels 7–9 grammar inventory
Supports directory placement at HSK 9 as an internal subdivision of the official advanced band; it does not independently prove usage rules.
Official source10 / CONTINUE
Continue with a Connected Rule
Compare
吗吗 and A-not-A Questions
Compare rhetorical inference with ordinary affirmative-negative questions.
Easy to confuse
无非/不过…而已/罢了无非...而已... (wúfēi...éryǐ)
Distinguish 莫非 suspicion from the minimizing 无非……而已 pattern.
Compare
何必何必 (hébì): Why Bother?
Compare surprised inference with a rhetorical challenge to necessity.
Compare
哪有X这么Y的 / 有这样Y的吗哪有…这么…的? as a Rhetorical Challenge
莫非 voices a suspected inference, while 哪有 rejects a proposition as unreasonable or extreme.
RECOMMENDED NEXT
Compare
Compare rhetorical inference with ordinary affirmative-negative questions.