美元为什么涨？这涉及到许多复杂的因素和全球经济的动态变化。以下是对这个问题的解析以及英文翻译对照：

首先，美元的涨跌受到国内经济因素的影响。当美国经济表现强劲时，投资回报高，吸引了全球资本流向美国市场。这导致了美元的需求增加，从而推高了美元的价值。此外，美联储的货币政策也会影响美元的走势。当美联储降低利率时，货币变得相对便宜，吸引了更多的投资和贸易。这也增加了对美元的需求，推高了美元的价值。英文翻译为：Firstly, the rise and fall of the US dollar is influenced by domestic economic factors. When the US economy performs strongly, high investment returns attract global capital flows to US markets. This leads to increased demand for the US dollar and pushes up its value. In addition, the monetary policy of the Federal Reserve also affects the trend of the US dollar. When the Fed lowers interest rates, money becomes relatively cheap, attracting more investment and trade. This also increases demand for the US dollar and pushes up its value.

其次，美元的涨跌也受到全球经济因素的影响。当全球经济形势不稳定时，投资者会转向美元等相对安全的资产。这增加了对美元的需求，推动其价值上升。此外，国际贸易的开展也影响美元的价值。由于美国是全球最大的经济体之一，很多国际贸易使用美元结算。当国际贸易增加时，对美元的需求也会增加，从而推高其价值。英文翻译为：Secondly, the rise and fall of the US dollar is also influenced by global economic factors. When the global economic situation is unstable, investors turn to relatively safe assets such as the US dollar. This increases demand for the US dollar and pushes up its value. In addition, the conduct of international trade also affects the value of the US dollar. As the United States is one of the largest economies in the world, many international trade transactions are settled in US dollars. When international trade increases, demand for the US dollar will also increase, thereby pushing up its value.

综上所述，美元的涨跌受到国内和全球经济因素的影响。这些因素共同作用，导致了美元的走势变化。英文翻译为：In summary, the rise and fall of the US dollar is influenced by both domestic and global economic factors. These factors act together to affect the trend of the US dollar.