Well, there's a straight line, a curved line, a zig-zag line, a dotted line, a broken line, a tree line, a timber line
, a skyline, I walk the line, a line up but no line down, in-line, outline, under line... Ah...then there's the bump line
(which I can see, but sometimes bail out of). Racers set an invisible line around the gates, which if followed correctly, will make your time faster, which is hard to do as well.
The there is the line you take when just crusing