their的形容词性物主代词和名词性物主代词

　　例句：

　　I joined my wail to theirs, loud and bitter.

　　我和他们一起恸哭，哭声又高又痛苦。

　　Japan's higher education is superior to theirs.

　　日本的高等教育比他们的好。

　　Both England and the US said the island was theirs.

　　英国和美国都说这个岛是他们的。