theory meaning

例句：

1. 1. The theory ofrelativity was proposed by Albert Einstein.
   爱因斯坦提出了相对论理论。
2. 2. The theorybehind the phenomenon is still under debate.
   这一现象背后的理论仍在争论中。
3. 3. The theoryof evolution has been tested and confirmed bynumerous scientific experiments.
   进化论已被无数科学实验证实。