보다 has two wide uses. - 보다 (normal verb): see, look, regard, consider - ~(아/어) 보다 (auxiliary verb): 1) (try smth and see what happens) do something for a trial; try doing smth; try and ... 2) (experience) has done smth; has the experience of doing smth 3) (guess, inference) it appears that...; appears to... Ex) - 이렇게 해 봐: Try it this way; Try this method. (trial) - 이것 입어 봐: Try this on. - 병원에 가 봐: Go to a hospital (to see what they say...) - 부산 가 봤어?: Have you ever been to Busan? (experience) - 피자 먹어 봤어?: Have you ever eaten pizza? - 키가 크나 봐: ... appears to be tall. (guess, inference) - 마음 상했나 봐: ... appears to be hurt (in feelings). - 알았으니 가 봐: OK, you can go now. (light command - more natural than 가 by itself) 봐 tend to make it smooth and natural in many contexts, so it is heavily used. Looking at your examples, (사람들이 나를) 이상하게 봐 (normal v): (people) regard me as strange. 즐겨 봤는데 (normal v): enjoyed watching 와 봤나 (aux v): =와 보았나. has ever come? (experience) 잘하나 봐요: appears good at smth. (guess) 보셨나 봐요: appears to have seen smth. (guess) 있나 봐요: appears to have it. appears to be there (guess)