[usually before noun] most important; essential最重要的；关键的；主要的◆Japan is a key market for us.日本是我们的一个主要市场。◆We identified five key areas for investment.我们确定了五个重点领域进行投资。◆They emerged as a key player in the pharmaceuticals market.他们在医药市场上崭露头角成为了主力军。◆This project is key to our financial success.这个项目是我们财政上成功的关键。