Why do you learn English ?

for lots of reasons

Explanation:

it is official languages of 53 countries and spoken around more than 400 million people across the globe.

its really important to know how to speak in English..

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.