过去,我一直认为雨水是水蒸气凝结成的,应该是最干净的。直到前几天,我偶尔想给我家的云松浇点水,这时正巧下大雨,就随手拿了一个杯子放到窗外接雨水(雨水浇花好,我妈妈这么说的),等到杯子里的水接满了拿进来一看,发现杯底沉着好多黑色小灰尘。这些灰尘是从哪里来的呢?雨水为什 In the past, I always thought that rainwater was condensed into water vapor and it should be the cleanest. Until a few days ago, I occasionally wanted to pour some water into my house. When it happened to be a heavy rain, I took a cup and placed it outside the window to receive rain water (my mother said it) and waited until the cup The water is full Take a look and found a lot of black bottom of the glass sinking small dust. Where did the dust come from?