i have eaten that food for thre years.

此句话有歧义.易理解为"我三年来一直在吃那个食物(只在吃食物)"不太妥.
修改:Nearly every meal in these three years,I ate that food.

for there years

不对 eat不是延续性动词 不能与for一起用
一定要用for的话 I have been eating that food for 3 years.

i have eaten that food for three years.

I have been having that food for three years.
我三年来一直在吃那个食物。（过去吃，并且至今仍然。）
（再具体点）
I have been having that kind of food for three years.
我三年来一直在吃那种食物。

给分吧~^^