Instead, the law called for the buses to be cleaned up with filters.

Today the power plants work with modern filters, and sewage works greatly improve the water conditions.

Every major e-mail program now comes with filters meant to spare you the trouble.

It was one of those things with filters in them.

Even with good filters, some of the spam makes it through.

Newer machines may use 96-well plates with individual filters in each well.

A ship equipped with filters is no better off when attacked than one without.

It is primarily used in conjunction with pipes and filters.

I said it was a healthier way to smoke, with filters.