How are you?

这是最常用的日常问候语，用于询问对方近况。通常回答为 “I’m fine, thank you.” 或 “Pretty good!”

How do you do?

这是一种较为正式的问候语，多用于初次见面。传统上应回答 “How do you do?” 而非直接说明状态。

How are you doing?

比 “How are you?” 更随意、更口语化，常用于朋友之间。可回答 “Doing great!”、“Not bad.” 等。

How is...?

用于询问某人或某事的状态，例如 “How is your mom?” 或 “How is the project going?” 回答应根据具体对象作答。