She had long ago learned to give nothing away by her expression.

He saw right through her, she could tell by his expression.

By his expression, no one had ever come up that way before.

I could see by her expression that she did not know.

She saw by my expression that the answer was no.

By his expression, I knew he would say nothing more about it.

But I could tell by her expression that he would.

It meant nothing to him, she could tell by his expression.

She could see by his expression that it worked, but not particularly well.

She saw by his expression that it did matter to him.