Man and woman are two parallel lines, and it is the nature of parallel lines never to meet.

男人与女人是两条平行线。两条平行线是不会相交的。

youdao

With a pen, you can shade by hatching (making parallel lines), cross-hatching (parallel lines crossing over parallel lines), scribbling, stippling, or making other funky little marks.

用钢笔的话你可以通过排线来制造明暗(画平行线)，交叉排线(平行线相交)，涂鸦，点绘或者其他时髦的笔触。

youdao

These lines,or circles,are parallel -- meaning that they are equally distant from each other at any point around the world.

VOA: special.2010.07.14

He scores the plate in parallel lines with the blowtorch, which heats the metal.

CNN: ASIANOW - TIME Asia | GizmoLand! | Man Beats Machine

M. tracing a star between two parallel lines, when he could see his drawing hand only in a mirror.

ECONOMIST: H.M.

At Smyrna, for instance, different body styles start out on parallel lines and are then brought together for painting and final assembly.

FORBES: Magazine Article