nǐ jiào shénme míngzi?
What's your name?
请说慢一点。
Please speak more slowly
This is a polite request: 请 (qǐng) means 'please', 说 (shuō) means 'speak', 慢 (màn) means 'slow', and 一点 (yìdiǎn) means 'a little'. Together it literally means 'please speak a little slow'.
请您说慢一点
qǐng nín shuō màn yìdiǎn
Please speak more slowly (polite form) — More formal and polite because it includes 您 (nín), the polite 'you'.
慢点儿
màn diǎnr
Speak slower — More casual and shorter, often used among friends.
你能再说一遍吗?
Nǐ néng zài shuō yī biàn ma?
Can you say that again?
当然,请说慢一点。
Dāngrán, qǐng shuō màn yìdiǎn.
Of course, I'll speak more slowly.
Appropriate
Avoid when
You say 请说慢一点 (qǐng shuō màn yìdiǎn).
It is pronounced qǐng shuō màn yìdiǎn. The third tone in qǐng rises slightly, and yìdiǎn has a falling-rising tone on yì and a falling-rising tone on diǎn.
Use it whenever you need someone to speak more slowly, especially if you are still learning Chinese. It is polite and appropriate in most situations.
Tomyo
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