Jack must keep solitary watch as there is no one else.

Now Jack couldn't keep the surprise out of his voice.

I wanted Jack to keep talking, something he liked to do anyway.

Jack kept looking at his watch; time seemed to move painfully slowly and each minute was like an hour.

Ever patient, Jack kept talking him through his mistakes, but with little success.

Jack kept coming across things he thought I really ought to have on hand.

Jack kept his place in front near the control panel.

Jack kept his head down and followed the car in front.

Jack also kept his eyes elevated to avoid looking down.

Jack saw no signs advertising for help, and kept on walking.