美元贬值的英文表达可以是 "dollar depreciation" 或 "devaluation of the dollar"。至于贬值的原因，以下是一些常见的英文表达：
1. Trade Imbalances: Due to trade imbalances, where the U.S. imports more than it exports, leading to a higher demand for foreign currencies and a decrease in the value of the dollar.
2. Interest Rate Differentials: A decrease in U.S. interest rates compared to other countries can make the dollar less attractive to investors, leading to depreciation.
3. Economic Slowdown: A slowdown in the U.S. economy can lead to a decrease in demand for the dollar, as investors seek safer or higher-yielding assets in other countries.
4. Political Uncertainty: Political instability or uncertainty in the U.S. can erode investor confidence, leading to a weaker dollar.
5. Inflation: If the U.S. experiences higher inflation than other countries, the dollar may lose value as it buys less in terms of foreign goods and services.
6. Supply and Demand: Simply put, if there is more supply of dollars than there is demand for them, the value of the dollar will fall.
7. Speculation: Investors may speculate on the future value of the dollar, leading to its depreciation if they expect it to weaken.
8. Currency Intervention: Central banks in other countries may intervene in currency markets to weaken their own currencies, making the dollar less valuable in comparison.
