1.bottom line 最重要的因素
The bottom line is that it's not profitable.
最重要的一点是它无利可图。
2.vaccinate against 接种疫苗
Have you had your child vaccinated against whooping cough?
你给你的孩子打过百日咳疫苗了吗？
3.protect against 预防
Exercise will not only lower blood pressure but possibly protect against heart attacks
锻炼不仅会降低血压，而且可能对心脏病有预防效果。
4.be exposed to 使遭受
They had not been exposed to most diseases common to urban populations.
城市人口中多数常见的疾病他们都没有接触到。
5.clinical trial 临床试验
Two rival laser surgery systems are undergoing clinical trials in the US.
两个相互竞争的激光手术系统正在美国进行临床试验。
