請回答第 38 題至第 42 題：
In 1368, a Buddhist monk called Chu Yuan-chang led a revolt in China against the Mongols, who ruled China at that time. His revolt succeeded and Chu Yuan-chang 38 a new family of Chinese rulers called the Ming Dynasty. The early Ming rulers extended the Great Wall of China, which had 39 been built to keep the Mongols out. They also brought the province of Yunnan 40 their control and forced Korea to pay a tribute to China. Soon, the Chinese decided to 41 from foreign contacts altogether. They were 42 and did not want anything from abroad. They regarded foreigners as barbaric, uncivilized people.