分离土壤中分解尿素菌的实验操作中，对于获得纯化的尿素分解菌的单菌落影响最大的是（ ）

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    There was a small river near Xue Yong's town．It went through several villages．The water was clean and there were lots of fish in it．

    Women would like to wash clothes along the river．It was a good place for them to talk about interesting things in their daily(日常的)life．Xue Yong liked eating noodles．So his mum often asked questions about how to cook noodles with different vegetables when she washed clothes there．

    It was also a good place for children．They caught fish and played water games there．At that time，Xue Yong had a small black dog．Every time he caught fish in the river,the dog followed(跟着)him．A fish was a good present for its work．

Now,Xue Yong lives in a city with his parents．

4.．They are interested in his town．Last Friday,Xue Yong and his parents watched a programme about some towns．Their town was one of them．

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