But in the end his efforts inevitably prove unproductive.

Of that encounter, I will say little, save that it proved tedious in the end and unproductive.

This, he did, and it too proved sublimely unproductive.

Observation of the Earth's surface proved unproductive, however, because of heavy cloud cover and bad photographic exposures.

It performed test drilling at the first site, which proved unproductive.

Though the concept would prove unproductive, the term became popularized in fiction.

Nevertheless, the waters east of the West Indies proved unproductive.

Their trip to the tiny local police station proved unproductive.

An interview with the girl may prove unproductive, but an interview is necessary to demonstrate that.

In consequence a few sessions proved unproductive, and items had to be attempted on successive occasions before she was satisfied with the results.