Some buildings that were destroyed and heavily damaged in the earthquake last year were constructed in violation of the city's building code.
A1)Some buildings,which were destroyed or heavily damaged in the earthquake last year,were
B)Some buildings that were destroyed or heavily damaged in the earthquake last year had been
D1)Last year the earthquake destroyed or heavly damaged some buildings that had been
Is A1 and D1 correct grammatically?
I think A1 should be a restricted clause ..since you are emphasizing destroyed or heavily damaged buildings only ... so you have to emphasize this fact so you need a 'that' instead of ',which' ...(read as comma + which)
I think D1 is correct. time can be mentioned either at the end of the sentence or beginning of the sentence, so I dont see any difference between B and D1 ..