HSK 9
莫非: Tentative Conjecture in Chinese
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.
STRUCTURE
莫非 + Subject + Predicate (+ 不成)?
When to use 莫非 — and when not
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？
Don't 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.
Right vs. wrong
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.
Examples
他今天一直没来，莫非生病了？
Tā jīntiān yìzhí méi lái, mòfēi shēngbìng le?
He has not come in all day; could he be ill?
门怎么开着，莫非有人进去过？
Mén zěnme kāi zhe, mòfēi yǒurén jìnqu guo?
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？
Nǐ yìzhí bù shuōhuà, mòfēi bù tóngyì zhège fāng'àn?
You have been silent; could it be that you disagree with this plan?
莫非我记错了日期？
Mòfēi wǒ jì cuò le rìqī?
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？
Tā zhème wǎn hái méi huílái, mòfēi wàng le shíjiān bùchéng?
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？
Nǐ píngshí bù rènzhēn xuéxí, mòfēi yào děngdào qīmò kǎoshì le cái kāishǐ jǐnzhāng ma?
Are you really going to wait until the final exam before you start worrying?
Common mistakes
他今天没来，莫非了生病？
Tā jīntiān méi lái, mòfēi le shēngbìng?
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？
Mén yìzhí kāi zhe, mòfēi bùchéng yǒurén jìnqu guo?
In the paired form, move 不成 to the end: 莫非有人进去过不成？
Think you've got it?
Write your own 莫非 sentence and check that grammar point first.
莫非: Tentative Conjecture FAQ
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？