Thanks a lot for your advices. I definitely need to catch up on my researches since I have been just doing what I was told to do in the past 3 semesters. =S Well, I did learn a lot from these 3 semesters tho. I will work on another independent research advised by a different prof next semester, and hopefully I can enjoy the experience and work on something interesting myself without the guidance of a grad student.
I have 1 more question regarding doing research with 2 profs simultaneously, I will make sure I have enough time in my schedule to work on both of them, but I am not sure whether it will make a bad impression on both or either profs. Since these 2 profs are in the same field, they have a few joint publications, and some of their works have been focusing on the same issue but from different perspectives. I think it would be quite interesting to experience both sides to see the different approaches they take regarding the same issue.