How do you say how have been in Thai?

There are several ways to say "how have you been" in Thai, depending on the context and formality:

Formal:

* สบายดีไหมคะ/ครับ (sa-bai dee mai ka/krap)? - This is the most common and polite way to ask how someone is. It literally translates to "Are you well?"

* เป็นอย่างไรบ้างคะ/ครับ (pen yang rai baang ka/krap)? - This is another formal way to ask how someone is. It means "How are you?"

* ช่วงนี้เป็นอย่างไรบ้างคะ/ครับ (chuang nee pen yang rai baang ka/krap)? - This is a slightly more formal way to ask how someone is, focusing on how they've been doing recently. It translates to "How have you been lately?"

Informal:

* สบายดีไหม (sa-bai dee mai)? - This is a less formal way to ask how someone is. It literally translates to "Are you well?"

* เป็นไงบ้าง (pen ngai baang)? - This is a very casual way to ask how someone is. It means "How are you?"

* เป็นยังไงบ้าง (pen yang ngai baang)? - This is another casual way to ask how someone is, similar to "How's it going?"

When responding:

* สบายดีค่ะ/ครับ (sa-bai dee ka/krap) - This is the most common response, meaning "I'm well."

* ดีค่ะ/ครับ (dee ka/krap) - This is a shorter and more informal way to say "I'm well."

* ไม่ค่อยสบายค่ะ/ครับ (mai kɔ̀i sa-bai ka/krap) - This means "I'm not feeling well."

Remember to use the appropriate polite particles (ka for female speakers, krap for male speakers) when speaking formally.