Is a clause "A" a tautology if and just if it contains both the atoms p and ¬p at the same time?

Question

I'm just starting boolean algebra, and I'm kind of stuck here.

I know $A=(p \text{ or } ¬p)$ is a tautology, and what I've tried to do is to find an example of a tautological clause that does not include $p$ or $¬p$ at the same time, without success.

Any help?