这得根据你什么时候,什么地点,跟什么人打招呼.比如：
特别熟的朋友：Hi,guy...
比较熟的朋友：how are you doing recently?
普通朋友：hello,what's going on with you?
长辈,老师：how are you today?
陌生人：excuse me.
第一次见面：how do you do,nice to meet you
little tip:我自己总结的,有错误希望大家给与指点,