垠

例句：

1. 1. The boundary between our two countries is very clear.
   我们两国之间的边界非常清晰。
2. 2. The researcher found that the boundary between science and art was blurred.
   研究者发现科学和艺术之间的界限变得模糊了。
3. 3. The philosopher pondered over the boundary between right and wrong.
   哲学家在思考正确与错误之间的界限。