Esperanto

My cousin has been learning Esperanto for two years and can already chat with people from several countries.

用法提示：句中 Esperanto 作名词，表示人造国际语言“世界语”。

Some people learn Esperanto because they want a neutral language for international communication.

用法提示：Esperanto 在动词 learn 后作宾语，指“世界语”这门人造语言。

The book explains the history of Esperanto and its role in the modern world.

用法提示：Esperanto 在介词 of 后作宾语，指“世界语”这一语言。