For a long time he looked deep into her face with a serious expression.

In fact, he usually had a very serious expression on his face.

It was a young woman, with a serious expression and her hair pulled back.

He looks slightly to his left with a serious expression.

Soon children with big brown eyes and serious expressions come to look at me.

She gave me a dark look and I tried to put on a serious expression.

He did not move, but looked at her with a serious expression on his face.

She turned to me, a serious expression on her face.

Jack looked at her with a serious expression on his face.

But he kept staring down at the ground, his expression serious.