2. reasons: a. the policy of closing the country to the outside world. B. long-term feudal rule. C. There was an industrial revolution in the West. D Due to foreign aggression, China's traditional agricultural economy went bankrupt, while the development of industrial economy was restrained and it became a semi-colonial and semi-feudal society.
3. A. Carry out reform and opening up. Second, focus on economic construction and vigorously develop productive forces. Implement the strategy of rejuvenating the country through science and education.
The rapid development of China's economy has injected new vitality into the development of the world economy and become the driving force for the sustainable development of the world economy.