许多食品含有化学品以保持新鲜。

Many food products contain ___chemicals to preserve freshness.

工厂在将废水排放到环境之前，必须进行处理以去除有害化学品。

Factories must treat their wastewater to remove harmful ___chemicals before releasing it into the environment.

这种清洁产品效果很好，但含有强烈的化学品，因此要在通风良好的区域使用。

This cleaning product is effective but contains strong ___chemicals, so use it in a well-ventilated area.