1. The base of selling RMB on a large scale is the same as buying USD on a large scale. Think about it. Selling RMB means selling RMB and buying foreign currency (USD). Buying dollars means buying dollars and selling RMB. This is just a question of the order of Chinese expression.

Second, buying a large amount of US debt every year is to reduce the amount of US dollars in the China market and return the US dollars received by China to the US Treasury, so that the reduction of US dollars in the market will increase the possibility of appreciation of the US dollar. The dollar naturally rises and the RMB naturally depreciates.