air mail

名词 air mail:

1. mail that is sent by air transport
2. letters and packages that are transported by aircraft
   同义词：airmail
3. a system of conveying mail by aircraft
   同义词：airmail, airpost

动词 air mail:

1. send or transport by airmail
   同义词：airmail

1. Surface mail or air mail?
   普通邮件还是航空邮件？