【正确答案】 Dear Editor,
I am writing this letter for the purpose of drawing your attention to the fact that some people still use plastic bags in spite of restrictions on the use of them. So I will try to make some conducive recommendations concerning the white pollution.
In my humble opinion, first of all, the public should keep in mind the negative influence of the frequent use of plastic bags. Besides, people should enhance the awareness of environmental protection, and use more environment-friendly bags than plastic ones. At last, the government should strengthen the relevant management.
I hope that you will find these proposals useful. Your prompt attention to my recommendation will be highly appreciated.
Yours sincerely,
Li Ming

【答案解析】 写信人开门见山表明自己写信的目的，即针对依然存在的白色污染问题而提出建议。第二段具体阐述了三方面的建议。第三段提出了对收信人的希望，自然得体，合情合理。全文语气诚恳、真切，语言简洁明了，达到了很好的交际效果。