I just do not know how much you know about electricity.

"Chances are," he said, "we know a little more about electricity than they do."

At that time only a little was known about electricity.

To explain myself, let me tell you some stories about electricity.

They probably used to say the same thing about electricity...

I remember being made to read aloud something about electricity a few weeks after starting school.

They use about 75 percent less electricity than ordinary bulbs and can last 10 times longer.

He knows more about electricity than the guy who invented it.

He knew very little about electricity; that was Hughes's job.

Even though they didn't fully understand it, ancient people knew about electricity.