1. 一流的;极好的;最优的    If you describe something or someone as first-class, you mean that they are extremely good and of the highest quality.

    e.g. The food was first-class...           食物一流。    e.g. She has a first-class brain and is a damned good writer.           她头脑相当灵光，是个非常棒的作家。

2. 甲级的;一等的;优等的    You use first-class to describe something that is in the group that is considered to be of the highest standard.

    e.g. He officially announced his retirement from first-class cricket yesterday...           他昨天正式宣布退出甲级板球赛。    e.g. Harriet graduated with a first class degree in literature...           哈丽雅特毕业时获文学一级学士学位。

3. (车厢、船舱、机舱)头等的，一等的    First-class accommodation on a train, aeroplane, or ship is the best and most expensive type of accommodation.

    e.g. ...a first-class carriage...           头等车厢    e.g. He won himself two first-class tickets to fly to Dublin.           他为自己赢得了两张飞往都柏林的头等舱机票。

4. 911查询·英语单词大全

4. (英)优先投递的，第一类的;(美)第一类邮件的(适用于信函和明信片)    In Britain, first-class postage is the quicker and more expensive type of postage. In the United States, first-class postage is the type of postage that is used for sending letters and postcards.

    e.g. Two first class stamps, please...           买两张第一类邮件邮票。    e.g. The price of mailing a first-class letter will not be increasing this year.           今年一类邮件的邮费不会增加。