on在什么情况下加介词on,什么情况下不加?答:in 2008;in spring/summer/autumn/winter;in September;in September, 2008;on September 10th;on September 10th, 2003, on Monday/Tuesday;on Christmas Day; on Women' s Day,on National Day(在国庆节那天)二、morning, afternoon, evening Hi this, that, next, last, tomorrow,yesterday...