Farmer Bob seemed to think this a proper line of investigation and was only too happy to tag along.

It was a pity that the economy hadn't developed along proper lines, but Clark wasn't a social theorist.

He had to check the floating object in exactly the proper line.

A proper first line in the response could be:

The tip hovered over the paper, and after a moment's hesitation, she wrote their name on the proper line.

Everyone else get in the proper lines for your homelands and register to be taken out.

Such words hold the key, or so officials hope, to discerning the proper line in a confusing period.

Time and place and proper lines of authority be damned.

Milling developed itself into a proper line of industry.

The second probe did not veer off its proper line.