wbcsguru.comwbcsguru.com/pdf/WBCSPrelimsPaper.pdf · (A) to bring oxygen for breathing. (B) so that...
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wbcsguru.comwbcsguru.com/pdf/WBCSPrelimsPaper.pdf · (A) to bring oxygen for breathing. (B) so that sunlight may enter the room. (C) to maintain convectional currents keep the air