词典释义：
a set of people or things grouped together as the best
第一流的人物（或事物）
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the first class of the orders of chivalry .第一流的骑士团。
[mass noun]the best accommodation in a plane, train, or ship
（飞机、火车、轮船的）头等舱
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a seat in first class .一个头等舱座位。
〈英〉 （大学学位考试成绩的）优等。
of the best quality or in the highest division
第一流的（地），一级的（地），甲等的（地）
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[as adj.]
the hotel offers first-class accommodation .该酒店提供一流的住处。
of or relating to the best accommodation in a train, ship, or plane
（火车、轮船或飞机的）头等舱的
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[as adj.]
a first-class carriage 头等车厢
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[as adv.]
you can travel first class on any train .你可以乘坐任何一列火车的头等车厢。
of or relating to a class of mail given priority
（邮件）优先投递的，第一类的
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[as adj.]
first-class mail 第一类邮件
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[as adv.]
send it first class .作为第一类邮件寄发。
[as adj.]
〈英〉 （大学考试）一等的，甲等的
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a first-class honours degree .甲等成绩学位。
(of cricket)played between sides of recognized stature and with matches of two innings per side
（板球）甲级赛．
