I am so exciting that I have the luck to attend his class.为什

excited形容人的感受,如,I felt excited when I heard the news.
exciting形容事物,如,an exciting football match
我觉得你只要记得要形容人感到,就要+ed
同类用法的此有interest, surprise, ruamaze, frighten, confuse, etc.
如：I am interested in sports.我对运动感兴趣（形容人的感受）
I found an interesting book.我找到一本有趣的书（形容事物）
He is an interesting man. 他是个有趣的人.（虽然形容人,但不是某人的感受）
总之,+ed一定是某人的感受