The foundation of democracy is the will of the people to preserve liberty

The foundation of democracy是主语
is是谓语
the will of the people是宾语
to preserve liberty是不定式做宾补

民主主义的基础就是保证人民享有自由
主语 The foundation of democracy
谓语 is
宾语 the will of the people
不定式做宾补 to preserve liberty

The foundation(主语) of democracy（定语） is（谓语） the will（宾语） of the people to preserve liberty（补语）

捍卫自由的人民意志是民主的基石!
好句!

民主的基石是－－人权

意译的。。。。

The foundation of democracy is the will of the people to preserve liberty。
民主的根基是人民保护自由的意志。
The foundation of democracy是句子的主语，系动词is是句子的谓语，the will of the people to preserve liberty是句子的表语。