Analysis of test questions: RMB appreciation means that the same RMB can be exchanged for more dollars, which is beneficial to China's import rather than export. 4 correct; For the United States, the depreciation of the dollar is conducive to exports and not to imports, so ① right, ② wrong; Foreign exchange reserves are mainly settled in US dollars. In the case of the depreciation of the US dollar, China's foreign exchange reserves shrank, which is correct; The answer c is correct.