英语语法分析

The United States was enjoying its “unipolar moment”;

美国一直在享受它的“单国时刻”；

The second is that America's role as the single pole of a unipolar world is inevitably coming to an end.

第二种变化在于，美国所扮演的单极世界中唯一一极的角色正在不可避免地走向终结。

In short, Japan is getting real-life experience of what maritime Asia would be like without unipolar America power.

简言之，日本正切身体验到，没有单极美国强权的情况下，亚洲沿海地区将会怎样。