this is _____the river was polluted

this is _____the river was polluted 1.This is no fish in this river because it has been polluted – Do you know why the river was polluted? This is the writer,_____the book was written three years ago this,river.is. 从句变分词：the water was from the river which had been polluted b The river was so polluted that it actually caught fire and b This is _____the league last year? The river is so seriously polluted that few fish,_____,can b The water in the river is polluted .Tom（）catch any fish in i Wastewater from factories polluted the river为什么用polluted This river is ____that one.