有问题的货品我们保证会退款。

Yǒu wèntí de huòpǐn wǒmen bǎozhèng huì tuìkuǎn.

We guarantee a refund on defective goods.

医生也不能保证病人能康复。

Yīshēng yě bù néng bǎozhèng bìngrén néng kāngfù.

The doctor cannot guarantee that patients will recover.

这个商店保证产品质量。

Zhège shāngdiàn bǎozhèng chǎnpǐn zhìliàng.

This shop guarantees the quality of its products.