既然大多数人知道艾滋病的传播途径，情况为什么还会这样糟糕呢？

Why is this so, when most people know how it is spread?

youdao

我明明输入的是正确的验证码，为什么还会这样？知道的告诉一下，谢谢！

I clearly enter the correct verification code, why would this be? Know to tell about, thank you!

youdao

父母都不理解，为什么在他们以为都正确的教导下女儿们还会犯这样的错误。

Parents who “did everything right” can't understand how it happened when their daughter falls on the wrong side of the stats.

youdao

And so these are situations where we would very much like to produce a vaccine, but we can't yet, and the question is 'Why? '.

我们十分想生产疫苗来解决这些问题,但我们还不行,你们会问,为什么会这样

耶鲁公开课 - 生物医学工程探索课程节选