Op D seems more tempting now as PRONOUN WHOSE can refer to many settlers logically...and more clear except, i didn't understand the use of tenses in this Op D...land was barren and houses had been seized...and finally settlers moved...
seems like houses seized first then land barren and simultaneously settlers moved..i believe the past perfect should be attached to both LAND and HOUSES and then simple PAST Tense, as its there for settlers moved..
no, the tenses are used properly in that sentence.
the past perfect should be used for an
event that had happened prior to, or up until, the event in question and was directly relevant to / influential on that event in some way.
for instance:
i had already studied for three hours when the professor announced her intention to cancel the exam. --> the use of the past perfect is appropriate here, because "had studied" is a PRIOR event (i.e., it was already
over when the professor announced her intention, and/or it terminated
at that time) that is relevant to that announcement.
for
general states of affairs, you should NOT use the past perfect -- you should use one of the following:
* the normal past tense, if the state of affairs generally persisted at the time in question but doesn't necessarily persist anymore
or
* the present tense, if the state of affairs is universal (including now)
for instance:
the settlers moved because their land was barren
--> this was a generally persistent state of affairs; i.e., the land didn't stop being barren as soon as the settlers decided to move. therefore, the past perfect would be inappropriate here; the past tense is what is required.
note also:
medieval doctors were usually powerless to stop infections once those infections had started, because the doctors were unaware of how bacteria propagate and can be killed.
this sentence is correct; note carefully the use of all three of the following tenses:
* "had started" is in the past perfect; this is a point event, PRIOR to the time in question, which has an influence on the situation described in the rest of the sentence.
* "were" is in the normal past tense, because the doctors' lack of awareness was a generally persistent state of affairs -- i.e., "had been unaware" would incorrectly imply that doctors actually became aware of the workings of bacteria at this point!
* "propagate" and "can be killed" are in the PRESENT tense, because these are general facts about bacteria that are still true even today.
--
also, don't forget:
verb tenses are generally the hardest aspect of any foreign language!
*NO* two languages have verb tenses that correspond exactly to each other -- every language has unique and extremely subtle rules governing when to use its different verb tenses. worse yet, those uses are largely unconscious for native speakers (i.e., exactly 0% of native speakers will be able to explain accurately how the tenses are used, unless they have actually studied those tenses formally for some other reason), so good explanations can be relatively hard to find.
