题目内容：

请帮我分析下这个句子,就是它的成分,
It is significant that the earliest living things that built communities on these island are examples of symbiosis.

优质解答

It 【主句形式主语】is【系动词】 significant 【表语】that the earliest living things {that built communities on these island }【定语从句】are examples of symbiosis【主句的真正主语,{主语从句}】.