theory ·noun (IDEA)
Definition: an idea or set of ideas that is intended to explain something Level: B2
达尔文的进化论从根本上改变了我们对生物学的理解。
Darwin's ___theory of evolution fundamentally changed our understanding of biology.
她提出一个理论，认为这座古代遗迹是用来进行天文观测的。
She has a ___theory that the ancient monument was used for astronomical observations.
爱因斯坦的相对论是现代物理学的基石。
Einstein's ___theory of relativity is a cornerstone of modern physics.