substance|substances

有机物质在环境中会自然分解。

Organic ___substances decompose naturally in the environment.

危险物质必须极其小心地处理。

Dangerous ___substances must be handled with extreme care.

许多家用产品含有各种化学物质。

Many household products contain various chemical ___substances.

化学家使用光谱仪识别了这种未知物质。

The chemist identified the unknown ___substance using a spectrometer.