名詞 first class:

1. the highest rank in a classification
2. mail that includes letters and postcards and packages sealed against inspection
   同義詞：1st class, first-class mail, 1st-class mail
3. the most expensive accommodations on a ship or train or plane

形容詞 first class:

1. of the highest quality
   同義詞：excellent, first-class, fantabulous

副詞 first class:

1. by first-class conveyance; with first-class accommodations
   同義詞：first-class

1. This ticket doesn't entitle you to travel first class.
   你這張票不能坐頭等位。
2. He always travels first class expense is no object.
   他出門總是用頭等票－－費用不成問題。
3. The crew was made up of strong and able men and the mates were experienced seamen of the first class.
   船上的全體船員都是強壯能干的人，大副二副們都是第一流的有經驗的海員。