3）苍蝇的启示

因为世界上找不到一块干净的地方，于是苍蝇为了生存，只能在肮脏环境中去当可怜而低下的清道夫。 The revelation of flies Because there is no clean place in the world, flies can only work as pitiful and lowly scavengers in dirty environments in order to survive.