Any information about a country and its people could be useful during a mission.

This distinction is useful in other ways, during discussion of language.

"It's useful for the kids during the cold bleak winter."

So evolution would never give us vision which is only useful for a couple hours during the day.

A birthing ball may be especially useful during back labor.

This is most useful during transitional stages of the partnership.

However, the phase change is useful during the operation of a nuclear weapon.

The administration believed that they would be useful both during a general war and to deter a local one in Europe.

A pair of pajamas can be especially useful during a delay.

Rapid style is useful especially during exhibition of playing skills.