Ammonium nitrate smoke, as an extremely persistent colloid, will also have to be removed.

Although legal intervention is often seen as a means of last resort in cases of extremely persistent truancy, the problem may, by then, have become too firmly entrenched.

However, it is an extremely persistent organic pollutant; it does not easily break down.

"He was extremely persistent," said his caseworker, Elizabeth Sanford.

The disease, which is believed to have originated in South East Asia, is extremely persistent when it becomes established in an area.

It is extremely persistent in soil and water and on most surfaces.

Quinn Barry was proving to be an extremely persistent and unexpectedly clever adversary.

I had grown one artemisia already, unfortunately: A. vulgaris, a European plant that is a troublesome and extremely persistent weed throughout the Northeast.

Although progress has been made over the past few years, social inequalities between men and women remain extremely persistent.

Pollution resulting from fine dust particles and ammoniac is extremely persistent.