And then, within each of those, they used a word that might need a definition, so in talking about classic epidemiology, they use the word etiology, in talking about clinical epidemiology, they use the word prognosis.

然后，个研究中，他们都使用了个可能需要定义的词，所经典流行病学时，他们使用病因学这个词，床流行病学时，他们使用预后这个词。

And later, I'll put back in a little definition of etiology, but we can do it much more quickly.

稍后，我将重新给出病因学的个小定义，但我们可更快地完成。