backgrounder记者招待会backgroundn.背景；经历；幕后；后景vt.提供背景background noise level背景噪声级background temperature背景温度Background Noise Power背景噪声功率background expectation背景期待background forecasting背景预测background illuminance背景照明background application后台应用程序background attenuation背景衰减background maintenance背景维护background color value背景颜色值