I didn't know he IS/WAS I didn't know he was/is such a good person.  Which is correct in the above sentence. Is/was and why ?  (Assume the person is still alive and is still a good person)
"He didn't know where New Jersey was" I know the past tense carries the past tense in every dependent clause, but referring specifically to places or to things that are eternal, like the Earth, seems a bit weird and therefore we sometimes (I believe incorrectly) say     He didn't know that New Jersey was actually on the East Coast.   Because it still is. Or     He thought the Earth was round.   So is it square now?  Logically speaking, would you consider the use of past tense here a bit confusing in a day-to-day speech in these examples? Would you instinctively opt for using the present tense?
Implicit 'which is', 'which are' A new study has shown that millions of pieces of junk floating in  space could be a big hazard for satellites orbiting Earth.   Is there an implicit 'which are' in front of floating in space? Why is 'which are'  not written?