President Obama said the current system has led the country to a breaking point, imposing hardships on middle-class Americans who struggle to pay for health care, who are unable to obtain it.

VOA: standard.2009.09.10

Because it challenged the whole class system, that people are born into a certain place and cannot-- and should not-- be moved.

因为它挑战了整个阶级体系，人生来就有阶级，不能-,也不应该被改变。

哈佛公开课 - 幸福课课程节选

I think that there's definitely a class system, but I also feel like everyone is very accessible,

我觉得，毫无疑问，这是种阶层系统，但我也感觉何种人都很容易接触到。

美国贫富差距？ - SpeakingMax英语口语达人

There's a whole class of antagonistic drugs that have been designed to influence your cardiovascular system.

现有一大类的拮抗剂类药物,全部是设计作用于心血管系统的

耶鲁公开课 - 生物医学工程探索课程节选

There is, if you know, a little bit of class system here in England.

在伦敦这里是有一点等级制度的。

热门工作 - SpeakingMax英语口语达人

Because people will find love in another class system

也因为人们可能在另一个阶层中找到自己的最爱。

美国贫富差距？ - SpeakingMax英语口语达人

The immune system, some cells of the immune system, in particular this class of T-cells called CD8 cells have receptors which recognize MHC1.

免疫系统,其中一些免疫细胞,特别是T细胞中的,CD8细胞含有可识别MHC1的受体

耶鲁公开课 - 生物医学工程探索课程节选

So, that's antigen presentation to this population of cells called cytotoxic T-cells, Tc, a subset of the class of T-cells in the immune system.

这些细胞被呈递给另一种细胞,这些细胞被称为细胞毒性T细胞,是免疫系统中T淋巴细胞的亚群中的一种

耶鲁公开课 - 生物医学工程探索课程节选