Even for basic products, demand varies from day to day and week to week.

The demands imposed on volunteers vary according to the type of trial.

Each player did whatever was needed to win, evincing unique skills as the demands varied from game to game.

And the demand for power in a Times Square building varies widely during a 24-hour period.

With a normal good demand varies in the same direction as income.

The environmental demands of particular townships do vary.

He or she also has to learn which strategies are acceptable in which classroom, since teachers' demands will vary.

However the demands they make of each student are rigorous and varied.

Peak demand also varies by the time of day.

Alberta's electrical demand varies substantially throughout the day and across the seasons.