商洽函 negotiation letter
叩问函 call-in letter
答复函 reply letter
请求函 request letter
奉告函 inform letter
联系函 contact letter
来函处理答复函 ??
订货函 order letter
任命函 appointment letter
庆祝函 celebrate letter
感激函 thank you letter
先容函 ???
约请函 invitation letter
联络函 contact letter
致歉函 apology letter
慰问函 condolence letter
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