chúfēi wǒ shēnqǐng yánqī, fǒuzé jiàshǐzhèng huì yúqī.

Unless I apply for a postponement, the driving licence will be overdue.

Breakdown of chúfēi wǒ shēnqǐng yánqī, fǒuzé jiàshǐzhèng huì yúqī.

• 我wǒ: I
• 会huì: will
• 申请shēnqǐng: to apply
• 驾驶证jiàshǐzhèng: driving licence

Questions & Answers about chúfēi wǒ shēnqǐng yánqī, fǒuzé jiàshǐzhèng huì yúqī.

What does 除非 mean here, and how is it different from 如果?

除非 means unless or only if in this kind of sentence. It introduces the one condition that can prevent the result.

So:

• 除非我申请延期，否则驾驶证会逾期。 = Unless I apply for an extension, the driver’s license will expire / become overdue.

This is different from 如果, which simply means if and does not carry the idea of the only exception.

Compare:

• 如果我申请延期，驾驶证就不会逾期。 = If I apply for an extension, the license won’t expire.

That is a normal conditional sentence.

• 除非我申请延期，否则驾驶证会逾期。 = Unless I apply for an extension, the license will expire.

This version emphasizes that applying for an extension is the only thing that will stop that outcome.

Why does the sentence use both 除非 and 否则? Do they always go together?

They often appear together in this pattern:

• 除非 + condition, 否则 + result

This is a very common way to say unless..., otherwise...

In your sentence:

• 除非我申请延期 = unless I apply for an extension
• 否则驾驶证会逾期 = otherwise the driver’s license will become overdue

So the whole structure is very natural and clear.

Do they always have to go together? No. You can sometimes omit 否则 if the meaning is already clear.

For example:

• 除非我申请延期，驾驶证会逾期。

This can still be understood, but with 否则 the sentence sounds more complete and explicit.