We're exposed to things that might cause cancer where weren't exposed to them before and so that might be a reason.

我们暴露于可能致癌的物质中,这些物质在以前是没有的,这可能就是原因之一

耶鲁公开课 - 生物医学工程探索课程节选

Justin So Justin said it could be new things that are around and you're exposed to stuff we weren't exposed to before and that's true.

贾斯汀,贾斯汀认为我们周围的环境,出现了很多新物质,并且人们暴露在前所未有的环境中,这是事实

耶鲁公开课 - 生物医学工程探索课程节选

Yeah, so you're asking, if for example, why do you need a booster of tetanus, because if I get exposed to tetanus wouldn't I have this rapid response?

所以你会问,举个例子来说,已经感染过破伤风杆菌的人,为什么仍然需要接种破伤风疫苗,身体不是应该马上对该病菌做出应答吗

耶鲁公开课 - 生物医学工程探索课程节选

Doctors in Ireland said Gaidar's health had suffered radical changes, but they concluded he wasn't exposed to radiation.

NPR: U.K. Investigators Visit Moscow in Litvinenko Probe

We haven't exposed it to the media, which is our mistake, but we will do it in the very near future.

NPR: Israel Delays Expansion of Lebanon Offensive

One theory to explain why early introduction is important holds that if babies aren't exposed early enough to certain foods, their immune systems will treat them as foreign substances and attack them, resulting in an allergy.

WSJ: Food Allergy Advice for Parents: Start Peanuts, Eggs and More Sooner