英语翻译 句子准确 没有语法错误

In 2003,the Bureaus of Health from Hualien and Taitung Counties granted permission to conduct a study of PHNs.
2003年期间,花莲和台东卫生局批准了一项对公共健康护士进行的调查研究.
Of Taiwan’s 32 counties,these two were selected for this study based on their superior demographics in representing Taiwan’s rural residents.
在台湾32个县中选出这两个县作为调查对象是基于他们在展现台湾乡村居民的人口统计学方面的突出表现.
All of the 265 PHNs working in these counties’ health stations were invited to participate voluntarily and anonymously in the study.Mailed questionnaires were delivered during the period between January and March,2004.A total of 231 questionnaires (87.2%) was returned and analyzed.
在这些乡镇的卫生机构中工作的总计265名公共健康护士被邀请可以自愿并匿名参加此次调查.调查表在2004年的一月至三月期间被寄出.总计231份问卷（占总体的87.2%）被收回及分析.