求翻译：而现在，塑料袋在制造方面做了很大程度的改进，有限定了使用的数量，街道上的塑料袋明显减少，使城市污染程度变小，环境污染也变小。是什么意思？

, Plastic bags in the manufacture of a large degree of improvement, have limited the use of the number of plastic bags on the street is significantly reduced, smaller urban pollution levels, environmental pollution is also smaller.

And now, in the manufacturing of plastic bags has done a great degree of improvement, have a limited quantity, the use of plastic bags on the street, the city is small, pollution and environmental pollution.

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Now, plastic bag manufacturing has a large degree of improvement, has limited the number of used, the marked decline in plastic bags on the streets, smaller urban pollution levels, environmental pollution is also smaller.

But the present, the plastic bag has made the very great degree improvement in the manufacture aspect, decided the use quantity limitedly, on the street plastic bag reduced obviously, causes the city pollution degree to change small, the environmental pollution also changed small.