It was said that 和 It is said that 的区别

问题描述:

It was said that 和 It is said that 的区别
It was said that some primitive people who ate deer could run as fast as the deer.
据说有些吃鹿肉的原始人能跑得象鹿一样飞快
为什么这里用was?而下面的句子用is?
It is said that honesty is the best policy.人们说诚实是上策.
It is said that thirteen is an unlucky number.据说13是一个不吉利的数字.
It is said that those who eat the most are the least healthy.据说吃得最多的人身体最差.

这是时态问题.下面的 三个句子都是表示一个“客观事实”,不宜改变,故用一般现在时.
而第一个句子根据语境能判断是过去的情况,故用一般过去时.