Among the (artificial) dialogues in the HSK4上 book (page 53) is:
I translate this to
The price is okay, it's just that I don't know if the quality is guaranteed.
I don't understand why 保证 is used here. It seems like it could just be 质量好不好 instead. It's possible that 保证 was added simply because the author was required to use the word 保证, not because it's normal to do so. The seller does not go on to offer a "guarantee", but just gives assurances of the quality.
But I'm not sure, as the usage might be different to what I'm accustomed to "guarantee" meaning (this book does that a lot---uses grammar and meanings that don't have English parallels).
Question: Why is 保证 in 价格还可以，就是不知道质量有没有保证?