1. The human species, according to the best theory I can form of it, is composed of two distinct races, the man who borrows, and the man who lends. 

2. In theory, the scheme sounds fine.

3. The biologist advanced a new theory of life.

4. We decided to test the theory experimentally.

5. She supports her theory with copious evidence.

6. This theory makes sense of an otherwise inexplicable phenomenon.

7. Later,findings verified the scientist's theory.

8. Did you ever swallow the conspiracy theory about Kennedy?

9. No serious historian today accepts this theory.

10. It was a theory unsupported by evidence.

11. Some scientists have rejected evolutionary theory.

12. These new facts make the theory improbable.

13. Freudian theory has had a great influence on psychology.

14. The experiment confirmed my theory.

15. In theory, basketball is a non-contact sport.

16. The theory is not yet scientifically established.

17. Einstein's theory marked a new epoch in mathematics.

18. Recent research seems to corroborate his theory.

19. Most of us don't hold with his theory.

20. We found further scientific evidence for this theory.

21. Are you able to verify your account/allegation/report/theory?

22. I subscribe wholeheartedly to this theory.

22. Sentencedict.com try its best to gather and build good sentences.

23. Huxley was an exponent of Darwin's theory of evolution.

24. The theory is irreconcilable with the facts.

25. Natural selection is a key element of Darwin's theory of evolution.

26. Both quantum mechanics and chaos theory suggest a world constantly in flux.

27. One theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites.

28. What are the reasons for his rejection of the theory?

29. Radio signals received from the galaxy's centre back up the black hole theory.

30. A scientist must produce evidence in support of a theory.