China has one of the world's oldest continuous civilizations, consisting of states and cultures dating back more than six millennia. It has the world's longest continuously used written language system, and the source of such major inventions as what the British scholar and biochemist Joseph Needham called the Four Great Inventions of Ancient China: paper, the compass, gunpowder, and printing.
English is the First or Second Language in the world this is the most useful language in the world. English is a major language of international business, diplomacy, and science and the professions.
Spanish could be very valuable for your business, studies or just for travelling. Spanish is the fourth most spoken language in the world. Namely in Central and South America, Spain and in big parts in the USA.