都是问候语,不同的是相互问候的人之间的熟稔程度,以及答话方式
How do you do?说话的两人初次相识,而且在是在比较正式的场合下.答：How do you do.
How are you?说话的人相互认识.答：I'm fine,thank you.And you?
How are you doing?你最近怎样?说话的人不仅认识,还比较熟.回答的时候可以具体一点,如：Not too bad,I just moved to a new place.
How are you怎么回答
1.If you must know, I feel terrible. 如果你一定要知道的话，我感觉糟透了。
2. Actually I'm a bit under the weather. 实际上我有点不舒服.
3. I'm hanging on. 还活着。
4. Been better. 不太理想。
5. Mustn't grumble. 没什么好抱怨的。
6. Can't complain. 没什么好抱怨的。
7. Not bad. 还不错。
8. So-so. 一般般吧。
9. Fair to middling. 还过得去。
10. I'm better than I deserve.
how are you doing怎么回答
i'm doing ok可以.
i'm doing fine, don't worry about me.
或者是（并不是很好)not really, but i think i can still handle it, thanks for your concern anyway.
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