I think - ~고 생각해 (Opinion)
고 생각해 is usually used when you are expressing your opinion on something like what people should and shouldn't do and what people should and should not be allowed to do etc.
Refer to Have to - 해야 한다, Allowed to - 해도 된다 and I like doing - 하는게 좋다, 하는걸 좋아한다 to learn following examples.
Attach 고 생각해 to the present informal written form of verbs.
- 그걸 해야 한다고 생각해 = I think we should do it.
- 공원엔 가도 된다고 생각해 = I think it's OK to go to a park.
- 우유를 마시는게 좋다고 생각한다 = I think it's good to drink milk
- 저녁에 일찍 자고 아침에 일찍 일어나야 된다고 생각해.= I think people should go to bed early at night and get up early in the morning.
- 건강해지기 위해 과일과 채소를 많이 먹어야 한다고 생각해. = I think people should eat a lot of fruits and vegetables to become healthy.
- TV는 많이 봐도 된다고 생각해요 = I think it's allowable to watch a lot of TV.
- 시간약속에 늦으면 안된다고 생각합니다 = I think it's not acceptable to be late for an appointment
- 책은 많이 읽는게 좋다고 생각한다 = I think it's good to read a lot of books.
- 청량음료는 많이 마시지 않는게 좋다고 생각합니다 = I think it's not good to drink a lot of soft drinks.