At that time, the distance across the ocean was thought to have been half what it is today.

当时，人们认为大西洋两岸的距离只有今天的一半。

In the distance, across the lake, a truck lumbered around a corner on the hill. Sunlight twinkled in its side-view mirror.

远处，在湖那边，一辆卡车蹒跚着转过山路的拐角处，它的观后镜反射出闪闪的阳光。

Diameter is the distance across a circle, the length of the line that goes through the center of a circle and touches both sides of a circle.

直径是穿过圆的距离，即通过圆心并与圆的两边相交的直线的长度。