I missed two lessons because of the mock exam at school. At first I worried that I would spend a long time staring at the screen. But the lessons are not boring at all, that I can quickly catch up the contents I missed. Now another calculation issue is solved, at least I don't have to be panic when I see some calculations about Kc. Chemical Equalibrium is one of the most difficult topics for me, but I guess I can get the marks confidently (if there is no careless mistake). I am looking forward to the second part of Chemical Equalibrium.