Tom Bradley was mayor of Los Angeles from 1973 to 1993, an era when the city had transformed from a collection of suburban neighborhoods to the second-largest city in the United States.
Tom Bradley was mayor of Los Angeles from 1973 to 1993, an era when the city had transformed from a collection of suburban neighborhoods to the second-largest city in the United States.
A. an era when the city had transformed. B. An era during which the city was transformed. C. An era that transformed it. D. During which era the city transformed. E. During which the city was transformed.
my reasons: from 1973 to 1993 which means a time period ,so we must use one word to express this period. here an era is very suitable to it .an era is appositive of from 1973 to 1993.
and from tense ,we know it is exact past time .so we must use past tense
so i choose B.
As to E,during which ,which exactly refers to 1993,it can not refer to from 1971 to 1993, since which can not stand for one preposition phrase.