Original documents must be sent by registered airmail, and duplicate by subsequent airmail.
If you send it by airmail, please put here " By airmail. "
如果是航空邮寄, 请在这里注明“byairmail ”.
I want to send this letter to China by airmail.
Please paste this " AIR MAIL'sticker on the envelope when you send it by airmail.
您要寄航空邮件时,请把这张 “ 航空邮件 ” 的贴纸贴在信封上.
Please act promptly and let us have your reply by return airmail.