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Dyfyniad Arddull ChicagoJones, Leo. New Progress to Proficiency: Self-study Student's Book. Đà Nẵng: Nxb Đà Nẵng, 2003.
Dyfyniad MLAJones, Leo. New Progress to Proficiency: Self-study Student's Book. Đà Nẵng: Nxb Đà Nẵng, 2003.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.