00:00Why do people go to the river often put a piece of paper and just to drink water?
00:02This is a history of the history to check the safety of the water.
00:06According to the previous view, if there is a piece of paper that has a piece of paper
00:09and there is a piece of paper that has a piece of paper or a piece of paper that will
00:10change.
00:11This will show that the water can be not safe to drink directly.
00:14Although the method is not a scientific method, it is not a scientific method of human being
00:17when it is a human being.
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