But they may have other devices, just as useful to them.

With all of the different components that make up a computer system, this is definitely a useful device.

Giving one's enemy something else about which to worry was an old but still useful device.

Two sources offering different accounts of the same issue or event, provide the history teacher with another very useful device.

"The building has become a very useful device to lure students in and give them an enthusiasm about learning."

What was once a useful but impractical device became cost effective by the early 1970s.

These people would never throw away such a useful device.

There are people, like my mother, who refuse to wear this useful device, saying it would not help them.

The researchers realize they have a long way to go to make any kind of useful device.

It could indeed be a useful device during the work ahead.