Tibet is in the southwest part of China. This month, it celebrates its 40th birthday. 西藏自治区于1965年9月正式成立。它骑在“世界屋脊”- 青藏高原上。Tibet has the world's highest mountain: Mount Qomolangma （珠穆朗玛峰）. Potala Palace （布达拉宫） is a famous building in Lhasa （拉萨）. It is very old and beautiful. 它始建于唐朝，人们称它为“世界屋脊的明珠”...