One study has calculated that the lifetime benefit to the local economy for a single additional student who completes high school is half a million dollars or more.
一项研究计算得出，每增加一名完成高中学业的学生，当地经济的终身效益将增加50万美元或更多。
2
The world is unlikely to lose 100 species a day, or half of all species in the lifetime of people now alive, as some have claimed.
世界不可能象某些人宣称的那样，每天灭绝一百个物种，或在人们有生之年世界一半的物种将消失。
3
Like most people, I'd never even heard of hyperparathyroidism - even though more than half a million of us will be diagnosed with it in our lifetime.