Dear Alex,
Thank you for your patience solutions, what if my teacher would say I bother, ha ha. My intuition told me, your answer is very detailed, I have to pause to ask questions. I think, my question on the BBS other posts can find the answer, so I can stop asking some questions too simple. Ha ha ..
Actually you can consider the integration of the problem on the BBS, a lot of people question the basic are the same. Don't you think so?
CCXIAN

Last edited by 2016CCXIAN; 05/21/16 03:00 AM.