theory

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.

理论上，旅程应该需要三个小时，但实际上由于道路施工，通常需要四个小时。

In ___theory, the journey ought to take three hours, but in practice it usually takes four because of roadworks.

总之，理论上你可以找到很多解决这个问题的方法，但实际上，一些未经许可狩猎的人并没有受到惩罚。

To sum up, in ___theory you can find a lot of solutions to this problem, but in practice, actually some people who hunt without permission aren't punished.

理论上，项目应该在周五前完成，但延误是常见的。

In ___theory, the project should be completed by Friday, but delays are common.