Research on the risk impact of insurance companies' investment in Chinese stock market 并列题名：Research on the risk impact of insurance companies' investment in Chinese stock market Research on the impact of policy events on volatility of Chinese stock market Research on the influence of air pollution on Chinese stock market Research on the mechanism of anti manipulation in the stock market Research on the risks of human capital investment in enterprises 并列题名：Research on the influence of air pollution on Chinese stock market Research on information eeffciency of QFII investment in China's capital market Research on funds operation in Chinese stock market Research on the issues of earning preannouncement in Chinese listed companies