听力原文：M: Chinese President Hu Jintao told global business leaders Thursday there is nothing to fear about his country's emergence as an economic superpower. Mr. Hu spoke to the APEC Chief Executive Officers' Summit through a translator. W: China's development will not stand in the way of anyone, nor will it pose any threat to anyone. Instead, it will only benefit peace, stability, and prosperity of the world. M: The CEO Summit in Busan is a side event of the Asia-Pacific Economic Cooperation gathering. About 800 senior executives from APEC's 21 member economies are attending. Over the past quarter century since economic reforms were introduced in China, its economy has quadrupled, raising its gross domestic product to more than $7 trillion. China attracts tens of billions of dollars of foreign investment a year, and its massive demand for energy and raw materials have driven up world commodity prices. President Hu promised Thursday to cooperate with other nations to ensure global energy security. How many member states of Asia-Pacific Economic Cooperation attend this CEO Summit in Busan?