There are certain topics about which I have nothing to say, and they covered almost every one of them that night.

We need you to question him on certain topics.

This places certain topics beyond the reach of the scientific method.

Anyone with a curiosity about a certain topic or hobby can start a 4-H club.

But there are certain topics which simply cannot be studied by this method.

There may be bad reasons why philosophers stay away from certain topics.

If a research team wants to know how 300 million people feel about a certain topic, it would be impractical to ask all of them.

Perhaps I might, very briefly, address certain topics that have been raised in this debate.

There are certain topics or types of questions we do not address; these can be determined below.

A lens is simply a page with information about a certain topic.