By watching them in action通過觀察他們的活動

in action在活動； 在運行中

He is a man gentle in manner but firm in action.

他是一個舉止文雅但行動堅決的人。

Everything they eat comes from hunting and gathering.他們的食物都來自捕獵和采集

come from來自； 起源于

We heard clink come from that room.

我們聽到那個屋子傳來叮當聲。

These creatures were believed to have come from outer space.

據信這種生物來自外太空。

as they set out to catch an evening meal for their families.為準備全家的晚餐出發前相見

set out to打算, 著手

They succeeded in what they set out to do.

他們打算做的事已經做成了。

The shepherd set out to look for the sheep that had wandered (away).

牧羊人出發去找走失的羊。