And that required enough explanation to keep him talking through dinner.

Much of what has occurred to you in recent days requires explanation.

What in the world, I wondered, has he found that still requires explanation?

But it's clear that there are matters here which require explanation.

This second controversy, however, requires more explanation than the first.

There are other points that might be touched upon, but I believe none of them require explanation.

The act of drinking wine is one that requires explanation.

How and why that is requires explanation beyond what can be given in a short question/answer forum such as this.

Technical writing may be on any subject that requires explanation to a particular audience.

But while requiring explanations he refused to listen to them.