Now, see this circle I'm marking off here?

你看这个圆？

And start by marking off all the ones that you already know.

从标出所有你已经知道的内容开始吧。

It's the same as to check off something, you are marking it off.

这与勾选某事一样，您正在标记它。

On either side of the road, for a mile before you reached the foot of the hill, stood tall osage orange hedges, their glossy green marking off the yellow fields.

在路的两边，在你到达山脚前一英里处，矗立着高高的橙黄色树篱，它们闪亮的绿色在黄色的田野上划出一道道。