Well, first it is important because it's--

说它重要首先是因为
you need to track what the population is eating

你需要探寻人们都吃什么
and also individual intake.

还有个体摄入量
These guys are just counting

这些人只负责统计
the number of people in the class for the registrar,

班级人数然后交给注册处
so they're not doing anything more nefarious then that.

所以他们不会做什么过分的事情
Population intake:

总体摄入量
how do we know

我们如何知道
what to recommend to people to eat?

该建议别人吃什么
How much Vitamin A should they have?

他们应该摄入多少维生素A
How many grams of carbohydrate or fat should go into a normal diet?

在正常饮食中应摄入多少糖或脂肪
Should people eat more of this food

人们应不应该多吃这种食物