Positive and negative are not simple export trade minus import trade. But look at the final value of current account and capital and financial account in the balance of payments. (Note: The government's international reserve account does not participate in the calculation)

If a foreigner buys machinery and equipment in a foreign country and transports it to China, he will expand his factory in China. Then the two accounts cancel each other out. NX remains unchanged and has no impact on GDP.

If foreigners change foreign exchange into RMB in China first, and then buy equipment and land in China, that's two different things.

This is divided into several stages. First, after foreign exchange is converted into RMB, the capital and financial accounts will form a surplus, and the current account will remain unchanged. NX has increased.

From the perspective of income method, GDP = C+S+T S+T. After foreign capital is converted into RMB, it must be deposited in the bank. Then savings increase.

Secondly, when he spends money on equipment and factories. The multiplier principle can double the demand, thus affecting all aspects.

That's my understanding.