Nick looked over his shoulder to see if anyone was behind him.

He looked over his shoulder to see her smiling at him.

He leaned over her shoulder to see what she was looking at.

He looked over his shoulder to see what had happened.

He looked over his shoulder to see how close the attack was coming.

I looked back over my shoulder to see if Mother was watching.

"You can't be looking over your shoulder to see what other people are going to do."

He looked over his shoulder to see how much help he'd get.

She looked over Richard's shoulder to see what he was doing.

Scott felt like looking back over his shoulders to see who was watching him.