Why has it been so hard and why does it continue to be difficult to identify these pluripotent cells within tissues?

为什么会那么难呢,为什么在组织中识别多能干细胞,始终困难重重呢

耶鲁公开课 - 生物医学工程探索课程节选

But for all that, thinking about those facts make it rather difficult, while you're thinking about the facts, to continue enjoying kissing the person.

但是尽管如此，想到这些事实让继续享受亲吻，变得困难了，当你想到这些事实时。

耶鲁公开课 - 死亡课程节选