Gettysburg address的一句話講解謝謝!

題目：

Gettysburg address的一句話講解謝謝!
It is for us,the living rather,to be here dedicated to the great work remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation,under God,shall have a new birth of freedom—and that government of the people,by the people,for the people,shall not perish from the earth.這句話的語法結構?我完成一頭霧水啊謝謝!

解答：

這段話有5個版本,下面這個版本是公認的,林肯的原話（網上可以聽到這段話錄音）是這樣的：It is for us the living,rather,to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced.It is rather for us to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation,under God,shall have a new birth of freedom—and that government of the people,by the people,for the people,shall not perish from the earth.
兩個句子主幹是it is for us to be dedicated to .這裡的rather不用翻譯,只是表示對比上文所說意思上的轉折.然後第一句的iving修飾us,就是活著的我們；which從句修飾unifinished work,什麼樣的未完工作.應當是我們這些活著的人在這裡爲那些犧牲的人已取得巨大進展但仍未完成的崇高事業奮鬥.
第二句It is rather for us to be here dedicated to the great task remaining before us應當是我們在這裡爲面前依然存在的艱巨任務奮鬥.然後後面跟了4個並列的that 從句來說明這個任務是什麼.第一個that從句from these honored dead we take increased devotion to that cause（我們會繼承先烈的目標更加努力）,然後這個從句里還有個從句for which they gave the last full measure of devotion來修飾cause（爲了這個目標他們竭盡全力奮鬥都最後一刻）.第二個that 從句里that we here highly resolve 後面又跟了個狀語從句that these dead shall not have died in vain修飾前面的動詞resolve（我們誓言犧牲的人不會白白犧牲）.第三個that 從句that this nation,under God,shall have a new birth of freedom（在天主之下的這個國家將獲得新生）.第四個that 從句and that government of the people,by the people,for the people,shall not perish from the earth （民有、民治、民享不會從地球消失）.
再問： that從句是什麼從句？
在主句里作什麼成分？
謝謝！！！
再答： 同位語從句，用來進一步說明前面某個名詞的具體內容，相當於名詞，與前面的名詞同位。在這段話里，幾個that 從句成分與「task 」同位。