英语语法分析

They do not own the land in perpetuity.

他们并不永久拥有这片土地。

《牛津词典》

The U.S. government gave the land to the tribe in perpetuity.

美国政府将这块土地永久性划拨给该部族。

《柯林斯英汉双解大词典》

So we have sufficient reason to carry forward and further develop it in perpetuity.

我们有理由永远把它继承并发扬光大。