One day after class, a student came up to me and recommended traditional Chinese medicine.

有一天课后，一个学生找到我，并向我推荐了传统中医。

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There's no one available on such short notice to take her class.

仅提前这么短时间通知，找不到人接她的课。

《柯林斯英汉双解大词典》

One person in the group should be prepared to report back to the class on your discussion.

应由其中一名组员准备向全班汇报你们的讨论情况。

《牛津词典》

I had not gone to one class since arriving in New York.

VOA: special.2009.07.18

One social class does not owe anything to another and we should not feel guilty about pursuing financial interests.

一个社会阶层对另一个阶层并没有亏欠,而且我们也不必为追求经济利益,感到内疚

耶鲁公开课 - 金融市场课程节选

This being a Game Theory class, there's at least one game we have to discuss and we've come to it now.

既然这门课叫博弈论,我们就得学习一下接下来要讲的模型

耶鲁公开课 - 博弈论课程节选

But charters also need to attract one class of candidates who are likely to be very keen on defined-benefit pensions: teachers who have already accrued years of pensionable service in public schools, and who want to keep accruing service so they can reach that rich third decade.

FORBES: Charter Schools, Pensions and Golden Handcuffs

It turned out that some of the best belonged to one class of chemicals.

NPR: Mosquito War: New Chemicals May Beat DEET

Transferring wealth from one class to another to artificially boost real estate prices only delays the inevitable and necessary reallocation.

FORBES: Why The Recession Recovery Remains Anemic