Why not find out what you are interested in and study it continuously.
我的回复(2012-5-3 14:58):Thank you for your visit! I know the interest is very important. But the key point is that I don't have a clear idea about my interest all the time.I just want to learn in my research field as much as I can and become an advanced material engineer in the future.So I wonder if it is necessary for me to get a PHD? To be honest , I have no so much interest in my research field ,or say,I have no interest in research,at least now for me.So how can I cultivate my interest in my research?