如果是说我今天下午要参加一个会议.
就是用将来时.
i'll have a meeting this afternoon.
如果是说我今天下午参加了一个会议,那就是用过去式.
i had a meeting this afternoon.
如果故事性陈述,用过去式或者一般现在时都可以
in this evening, every girls wears their best shoes.