莫非 (could it be that …?)

An absence leads to a tentative guess

• A friend is very late. You wonder whether they forgot the meeting.
• he / him他tāstill / also还hái没来méi lái，can it be possible that莫非mò fēito forget忘wàng(completed / change)了le(concept of) time时间shí jiān？ — The speaker offers a possible explanation with surprise.

Locate the pattern in real examples

• can it be possible that莫非mò fēi (could it be that …?): can it be possible that莫非mò fēiyou你nǐto forget忘wàng(completed / change)了lewe / us我们wǒ men(of / 's)的deto agree on sth (after…约定yuē dìng?; he / him他tāto / arrive到dàonow现在xiàn zàistill / also还hái不来bù lái,can it be possible that莫非mò fēivariant of 出 (classifier…出chū(completed / change)了lewhat什么shén mematter事shì?
• Read the whole clause before choosing a translation. The examples show the pattern in use; the context below determines what the speaker claims.

Follow the speaker

could it be莫非mò fēiyou你nǐforget忘wàng了le？

• In the opening situation: he / him他tāstill / also还hái没来méi lái，can it be possible that莫非mò fēito forget忘wàng(completed / change)了le(concept of) time时间shí jiān？
• The speaker offers a possible explanation with surprise.

Check the limit of the explanation

• can it be possible that莫非mò fēi is a guess, not confirmation.
• A following question or reply may test it. since既然jì ránto forget忘wàng(completed / change)了le(concept of) time时间shí jiān would treat the forgetting as established instead.

Repair the form before interpreting it

• The form do not莫mò(completed / change)了leto not be非fēito forget忘wàng(completed / change)了le(concept of) time时间shí jiān needs repair here. Write can it be possible that莫非mò fēito forget忘wàng(completed / change)了le(concept of) time时间shí jiān instead; keep the word or frame in its demonstrated order.
• Form and meaning are separate checks. After the repair, explain the sentence in its situation rather than treating a familiar translation as a universal rule.

Keep the distinction

Read the full reference: HSK 6 grammar — Sentence patterns.