If you have not heard what a caller said, it is much more polite to say "I'm sorry. Could you say this again, please?" than to simply say "What?"

如果你还没有听到打电话的人说了什么，更礼貌的说法是：“对不起。你能再说一遍吗？”而不是简单地说：“什么？”

youdao

I'd like to call on you there if I have the chance. I am awfully sorry that I have forgotten your Korea name. Please say that again so that I can keep it in mind.

我有机会一定到韩国找你，你给我的韩国名字我暂时忘了，你是否可以告诉我。

youdao

I'd like to call on you there if I have the chance. I am awfully sorry that I have forgotten your Korea name. Please say that again so that I can keep it in mind.

我有机会一定到韩国找你，你给我的韩国名字我暂时忘了，你是否可以告诉我。

youdao