using the best and most expensive seats or accommodation in a train, plane or ship 乘坐头等座位(或车厢、舱) to travel first class 乘头等舱旅行
(in the UK) by the quickest form of mail (英国)按最快投递邮件 (in the US) by the class of mail that is used for letters (美国)按第一类邮件