It is also a useful substitute for sesame seed oil in Chinese cookery.

Frozen or fresh sea foods can be useful substitutes for live foods.

Thus, you are not a useful substitute for Tiberius.

Further research is now being conducted in primates to see if it will be a useful substitute for treating drug addiction in humans as well.

Proponent may be a useful substitute.

"Maybe it would be a useful substitute for the classes," he said, flipping through the pages.

An oil bubbler may be a useful substitute.

Guar gum has also proven a useful substitute for locust bean gum (made from carob seeds).

I suppose that . . . could be a useful substitute in some cases.

This makes a prism a useful substitute for a mirror in some situations.