1. Why did China have a favorable balance of trade with Great Britain until the Second Opium War?

The increasing flood of opium into China was causing all manner of social problems (including corruption with colluding local officials). Attempts by China's rulers to curtail this flood -- while still refusing other forms of trade -- irritated the British. So too did the official Qing position that the British and all other foreigners were vassals and barbarians. As China attempted to shut off the flow of opium, Britain and other trading countries resisted every measure. Conflict became inevitable.

They were both presidents.