At that moment, susceptible people become infected at exactly the same rate as infected people become removed.

此时，易感群被感染速度与感染者转归速度完。

Then, we step ahead in time, and the proportions in each group change according to the model's equations: some susceptible people become infected and some infected people become " removed" , by recovering or dying when enough time passes.

随着时间推移，每一组中比例根据型方程式而变化：一些易感者被感染，一些被感染足够长时间后通过康复或死亡而被“转归”。

And finally there's the " removed" group, the people who have already had the disease and have either recovered and gained immunity or, sadly, died of it.

最后是“转归群”，他们已经患病，或者已经康复并获得免疫力，或者不幸地死于该疾病。

And, the decrease of the number of infectious people over time is equivalent to the increase in removed people.

并且，随着时间推移，感染数减少当于转归组数增加。

But some people will also be recovering or dying, which means people will move over time from the infected to the removed group.

但是有些也会康复或死亡，这意味着随着时间推移，们会从感染群体转移到被转归群体。

And Assumption Three: after people are infected for a while, they move to the removed group, since they've recovered, or sadly, died, and can't transmit the infection anymore.

们被感染一段时间后，他们会转移到转归组，因为他们已经康复了，或者不幸是，已经死了，不能再传播感染了。