dual sources的用法和樣例：
例句
- Also shown are huge clouds of multimillion degree gas and bright point like sources due to neutron stars and black holes.
同樣顯現在其中的是巨大的氣體雲團，溫度達幾百萬度，還有明亮的點源，這是由於中子星與黑洞造成的。 - The distribution of non-point sources of pollution from different effluents had distinct spatial characteristics.
各流域非點源污染的發生具有明顯的地域分異特徵。
