I do not know what GWD offers. It is hard to tell you what to do next. To understand each question fully and have your own approach are the key. If you use his approach and get 80% right, why not just modify the approach based on your own understanding of CR? I feel that self-developed approach is hard to forget.
thanks a lot, mindfree. what i am doing now is to review the previous CR problems and try to understand the rational connection between the answers and questions.
My test time is approaching, do you think i should do LAST to improve my understanding of CR?