Reduced sounds are all those extra sounds created by an absence of lip, tongue, jaw, and throat movement.

They are a principal function of intonation and are truly indicative of the American sound.

结构：be + indicative(adj) + of + 名词

He has lived in Beijing all his life - Indicate a period inclusive of the present, from which it follows that he is still alive.

结构：be + inclusive(adj) + of + 名词

以上2句都出现了 be + adj + of + 名词的用法，请问这种用法中的of是什么用法，应如何理解？