Hello native English speakers.
Query about my guess about the one sentence original.
Let me quote from that portion of his testimony, which appears on pages 512 and 513, which makes it clear that he wasn't ever claiming that he spotted that verb tense at the time in the Jones deposition, and his silence or his answer was based on spotting the verb tense then. (original)

Question: By grammar & logic, what I guess is as follows:
①there is a noun before the preposition "from", which denotes the object of the verb "quote" here but which is omitted(we can not see it);
② both which's are referring to the same "noun" which we can not see due to being omitted;
③ the pronoun "it" here denotes two things :
(a.) he wasn't ever claiming that he spotted that verb tense at the time in the Jones deposition,
and (b.) his silence or his answer was based on spotting the verb tense then.
④ at the time in the Jones deposition, I guess , = at the time in the Jone's deposition, or rather, at the time when Jone spoke about or claimed his deposition.
⑤ the verb tense then = (my guess) the verb tense which when Jone made his deposition he used at that time.
Are my all guesses correct according to grammar and the original? Which is/are wrong?

Question

Hello native English speakers.
Query about my guess about the one sentence original.
Let me quote from that portion of his testimony, which appears on pages 512 and 513, which makes it clear that he wasn't ever claiming that he spotted that verb tense at the time in the Jones deposition, and his silence or his answer was based on spotting the verb tense then. (original)

Question: By grammar & logic, what I guess is as follows: 
①there is a noun before the preposition "from", which denotes the object of the verb "quote" here but which is omitted(we can not see it);
② both which's are referring to the same "noun" which we can not see due to being omitted;  
 ③ the pronoun "it" here  denotes two things : 
(a.)   he wasn't ever claiming that he spotted that verb tense at the time in the Jones deposition, 
 and (b.) his silence or his answer was based on spotting the verb tense then. 
④ at the time in the Jones deposition, I guess , = at the time in the Jone's deposition, or rather,  at the time when Jone spoke about or claimed his deposition.
⑤  the verb tense then = (my guess)  the verb tense which  when Jone made his deposition he used at that time.
Are my all guesses correct according to grammar and the original? Which is/are wrong?

Answer

1.  "Quote" has no object and does not need one.  It is used the same way you would use the verb "read":  "Let me read from this book".
2.  Both occurrences of "which" refer to "portion".
3.  "It" has no effect on the meaning of the sentence.  You can strike it out and nothing changes.
4.  Your guesses are as good as mine. This is a lousy confusing sentence.  The adverbial clause "at the time..." could be attached to many things.  When forced to choose, I always attach a clause to the closest plausible thing.  In this case, that would be "spotted".
5. I have no idea.

I suggest that you not torment yourself by trying to make sense out of needlessly complicated prose. It will not help you learn. Find clear well written prose.