I looked back once and had to close my eyes.

I looked back once, and of course he was gone.

I could not bring myself to look back even once at my wife and child.

She looked at me once, from across the room, feeling my eyes on her.

Once again looking around, I don't see anything out of place.

She never looked back once to see what Peter was doing.

The man looked back once at the L500 and then continued on.

He looked back only once, then led them down the hill.

I looked back once, just before we went into the trees.

As they left the church, she'd turned to look back once.