Graph paper, parallel, and planimeter methods are current tools for acreage calculation.

目前常用的量算积方法有方格纸法、平行线法、求积仪法。

Parallel lines are lines that never join.

平行线是永不相交的线。

Parallel lines are, by definition, lines on the same plane that never join.

按照定义说, 平行线是在同一平上永不相交的线。

Zollner's illusion makes parallel lines seem to diverge by placing them on a zigzag-striped background.

将平行线置于锯齿形条纹背景上，左氏错觉会让平行线看起来不平行。

There are two parallel lines.

这有两条平行线。