The action of oil and natural gas created hydrogen sulfide in the limestone.

VOA: special.2009.12.07

An agonist is a substance that mimics the action of a natural ligand, and I show you a couple of examples of agonists here.

激动剂是能够模拟天然配体分子的物质,在这里我给出了一些激动剂作为例子

耶鲁公开课 - 生物医学工程探索课程节选

This would an example of a substance that inhibits the action of a natural ligand and they can inhibit in a variety of ways.

这类物质能够以多种方式,抑制天然配体的作用

耶鲁公开课 - 生物医学工程探索课程节选

Not at all.Aristotle emphasizes the mutable character of natural right in part to preserve the latitude the freedom of action required by the statesmen.

绝对不是！亚里士多德强调,自然权利的易变特质部份,是要保留回旋余地,政治家所需的行动自由。

耶鲁公开课 - 政治哲学导论课程节选