Everyone knows that fish make up the fourth and last class in the vertebrate branch.

大家知道鱼类是脊推动物门中的第四纲和最后一纲。

What I learned until fourth class back then was better than what children have in 10th Grade now.

我小时候在四年级前学到的知识比现在上十年级的小孩学到的更多。

This is evidently a distinct fourth class.

这显然是一个独特的第四类。

The fourth class consisted of people who, according to Nekhludoff, were reckoned among the criminals only because they were morally above the average level of society.

第四类人，按照聂赫留朵夫的说法， 仅仅因为他们在道德上高于社会平均水平而被算作罪犯。

In the course of the day I was enrolled a member of the fourth class, and regular tasks and occupations were assigned me: hitherto, I had only been a spectator of the proceedings at Lowood; I was now to become an actor therein.

那天，我被录取为第四班的一员，并被分配了常规的任务和职业：迄今为止，我只是在洛伍德的旁观者；我现在要成为其中的一名演员。