如果和老外聊天没听清他前面说的话，我怎样说让他重复一遍更礼貌？

slowly,please.i can't get it.
请说的慢一点，我没听懂。
i beg your pardon?(pardon?)
请再说一遍

Sorry, I didn't hear what you said. Beg your pardon, please.
OR:
I'm sorry that I didn't catch up with what you said. Could you please slow down your speed?

I beg your Pardon！ 或是Excuse me