I finally found that I'm too lazy. My god, all the lecture note, I haven't for once read through every single word in the slides. There's no wonder that I do not understand fully. But I myself knows that was all along the problem. That's especially so since last year. But After I force myself to read throught 2 lecture notes, I could do one question, all myself, although it might not be the correct answer. And I feel satisfied. And now I should go and sleep. Mr BLOG at 4:00am