精车表面粗糙度Ra可以达到（）um。
A. 1.6-0.8
B. 12.5-6.3
C. 50-12.5
D. 0.02-1.25
When the law is implemented, the awareness of environmental pollution can be enhanced
A. 对
B. 错
Since the invention of plastic bags, our life has been facilitated to the largest extent.
A. 对
B. 错
Which statements about the use of plastic bags are ture?
A. Initiating a law which strictly bans the use of it.
B. Supermarkets or shopping malls should provide the bags for free or with a minimum charge.
C. Reducing to produce plastic bags those made from non-degradable materials.
D. Encourag ordinary shoppers to reuse the bags by giving them discount.
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