2--Let's take a look at this conversation:
 
1--Hey, what's up?
 
2--What's up? How are you?
 
1--I'm doing fine, thanks.
 
2--This phrase is a casual expression and is normally used when you're talking to friends, family, or colleagues.
 
1--You would not want to use it in a formal or business situation.
 
2--"What's up?" is a greeting.
 
1--It's a different way of saying "What's happening?"
 
2--When you ask someone "What's up?" in a conversation, it's another way to say: hello, ask how things are going, how the person is feeling.
 
1--It's a common greeting used by just about everybody in America!
 
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注解：
 
1.conversation对话
2.casual随便的  
3.situation情况   

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译文：

1--你听人们说过：怎么了？怎么了？怎么了？怎么了？（what's up? ）
2--来听听下面这段对话吧：
1--嘿，近来怎样？（what's up? ）
2--近来怎样？你怎么样？
1--我很好，谢谢。
2--这是一个日常短语，一般用于朋友、家人、同事之间。
1--不能在正式场合和商务场合使用。
2--“近来怎样？”（what's up? ）是问候语。
1--这是“发生什么了？”另外一种表达方式。
2--当你问某人“近来怎样？”（what's up? ），意思是说：你好，事情进展得怎么样了，心情怎么样。
1--这是美国人经常用的见面语！