1) 더 More 밥 더 먹고 싶어요 I want to eat MORE rice/food. 더는 공부하세요! Study MORE! 2) 또 Again (a synonym 다시) 또/다시 해 봐요 Try to do it AGAIN. 3) 도 Also, too (always attached to a noun) 이것도 주세요 Give me this one TOO. / ALSO give mi this. 요즘 저도 피곤해요 These days I feel tired TOO. / I ALSO feel tired lately.

I just want to add that 도 isn't just to say "too", "as well", "either/neither", "nor", it is also a particle for "even if". For example: 설령 그녀가 오지 않더라도 나는 개의치 않겠어요 (I won't mind even if she doesn't come.) 싫더라도 꼭 해야 돼요. (Even if you don't like it, you must do it.)