GMAT Sentence Correction (SC) | Re: In London that afforded its playwrights only two theaters ,

i learn the following point from a verbal expert (in the question "in an america...", pls google to find"

a+proper noun is used to show an aspect of that noun. this is high point of grammar .

London have many aspect. but I want to say about the London which has an aspect A. in this context , there are many London, each of them having an aspect.

in a London A
in a london which provide playwrights only two theaters.

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