"I understood, too, that in ordinary civil administration this oath even forbade me to practically indulge my primary abstract judgment on the moral question of slavery."
<span>Means that the oath he took when he(Abraham Lincoln) went into office and became president forbids him to do something that breaks the constitution no matter if his OWN morals say something else.
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"I had publicly declared this many times and in many ways; and I aver that, to this day I have done no official act in mere deference to my abstract judgment and feeling on slavery."
<span>He publicly said this to show every one his views on slavery different ways and he states that to that day he's done no official act to defend his judgement and view on slavery.
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"I did understand, however, that my oath to preserve the Constitution to the best of my ability imposed upon me the duty of preserving, by every indispensable means, that government, that nation, of which that Constitution was the organic law."
<span>He understood that his oath to preserve the constitutions to the best of his ability by any means necessary because the constitution was the main law.
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"Was it possible to lose the nation, and yet preserve the Constitution?"
<span>He looks for an alternate way to find a way to preserve the constitution without losing the nation.</span>
C) look beyond the details and imformation provided
I understand the topics of expositor and functional text. However I cannot see the passage you are talking about.
I would chose D) They seldom come nearer to it than planting-time, harvest-time, cherry-time, spring-time, or fall-time.
-Hiadamcom/Agarvated
