【正确答案】 Mandarin, the official language of China, is suddenly hot in American schools. As China becomes the world's leading economy in this century, both public and private schools are scrambling to add Mandarin to their roster of foreign languages or expand Chinese language programs. By some estimates, as many as 50,000 children nationwide are taking Mandarin in American schools. Promoting the development of Chinese-language programs has met some difficulties. A shortage of trained, credentialed teachers has made it difficult for some schools to join the race. When schools need to employ teachers, they often recruit them from China directly, which is a hidden trouble for a culture clash.