实验室过滤化学溶液以去除污染物。

The laboratory ___filters the chemical solution to remove contaminants.

气体通过特殊膜过滤以净化。

The gas is ___filtered through a special membrane to purify it.

你应该在饮用前过滤自来水以确保安全。

You should ___filter the tap water before drinking it to ensure safety.