The list of questions provided beforehand proved to be a useful aid and stimulant to the discussion.

The Shadow had found the little spotter to be a useful aid.

Clinical assessment for learners is a useful aid here in monitoring the progress achieved.

At present, computers are a useful aid in research, but they have to be directed by human minds.

The huge map of the battle is a useful aid to understanding it.

Finally, there are advertising agencies who can often give useful aid on certain aspects of recruitment.

Dark lines on paper can be a useful writing aid.

Cost effectiveness estimates should not be used in a mechanistic fashion; at best they provide a useful aid for decision making.

The radar return and general performance characteristics make it a useful aid in training.

This document has proved to be a useful aid in the current discussions, and is currently being revised.