一.如何打招呼

通用版:

1.How are you?

2.How are you doing?

3.How you doing?

4.How's it going?

4.How's everything going?

好久没见的朋友：

It's been a while. How've you been? 好久不见。最近怎么样

It's been a long time. What have you been up to? 好久不见。最近忙什么呢？

Long time no see. How are things treating you? 好久不见，过的怎么样？

熟人，非常不正式的场合，年轻人之间：

Hey, what's up?

Hey, what's going on?

回答时不用形容词 good/bad等词回答。

二.别人说thank you时该如何回答。

通用版:

1.You're welcome.

2.No problem.

3.No worries.

4.Don't worry about it. It's no biggie.

5.No sweat.

最好只在熟人之间用：

1.Sure.

2.Yeah.

三.别人说sorry时该如何回答。

通用版:

1.It's okay.

2.It's alright.

3.No problem.

4.No worries.

5.Don't worry about it.

6.Nah, it's no big deal.

7.No sweat.

最好只在熟人之间用:

Sure.

当然还有其他表达方法，但是这些是相对而言用的频率最高的一些。