We are responsible to replace the defective ones.
我们保换质量不合格的产品。
It's really something wrong with the quality of this consignment of bicycles.
这批自行车的质量确实有问题。
I regret this quality problem.
对质量问题我深表遗憾。
We hope that you'll pay more attention to the quality of your goods in the future.
希望贵方将来多注意产品的质量问题。
The workings of these machines are inaccurate.
这批机器运行不准。
Upon arrival, we found the shipment of wool was of poor quality.
货到后，我们发现羊毛的质量较差。
The quality of the fertilizer is inferior to that stipulated in the contract.
化肥质量次于合同中规定的。
The quality of this article cannot qualify for first-class.
这批商品的质量不够一等品。
If you find the quality of our products unsatisfactory, we're prepared to accept return of the rejected material within a week.
如果贵方对产品质量不满意，我们将在一星期内接受退货。
More than 300 watches are not up to standard.
有300多块手表不合质量标准。
　
Words and Phrases

bad quality 劣质
low quality 低质量
inferior quality 次质量
to be responsible for 对...负责
inaccurate 不精确的
poor quality 质量较差
to be inferior to 次于...
first-class 一等品
unsatisfactory 不满意的