But, unfortunately, there aren't good animal models for many of the diseases that we'd like to study.

但是很遗憾的是,对于很多我们想要研究的疾病,并不能找到合适的动物模型

耶鲁公开课 - 生物医学工程探索课程节选

And then they say, "We don't need an extra player, sorry."

但他们却说，“我们已经招满队员了，很遗憾。”

I was 课堂 - SpeakingMax英语口语达人

Although I don't quite understand--I should say, there's many things about how the fighting went on which we can only attempt to imagine because we just don't have films of ancient hoplite battles, I'm sorry to say.

虽然我有时也很困惑,比如说,战场上瞬息万变,情况非常复杂,由于没有古代重步兵白刃战的影像资料,我们只能猜想战场上发生了什么,真的是很遗憾

耶鲁公开课 - 古希腊历史简介课程节选