加点部分原来翻译为：...when a ticket had to be bought to take the train and a letter of introduction had to be shown to stay in a hote.

但读了这个译文马上产生了疑问：哪个国家乘车不购票呢? 人民公社之前我们乘车不用购票吗？在仔细查看原文，发现句子结构可以产生歧义，加点部分既可以理解为“乘车购票制度”和“住宿的介绍信制度”，也可以理解为“乘车购票的介绍信制度”和“住宿的介绍信制度”，根据常识判断，显然后一种理解更符合逻辑。这样的常识性错误是谁都可能犯的。可以改译为：

Later, when the people's commune was established, when coupons were needed to buy foodstuff，when a letter of introduction was needed to buy a train ticket and to stay in a hotel，and when a person had to apply for a permit for temporary residence in the city, it became practically impossible for large numbers of rural people to come to the city. But there has always been a small group of marginalized "aimless drifters".

例3.

1997年，中国全国人大常委会通过了《献血法》。在此之前1996年国务院行政法规《血液制品管理条例》和在此 之后1998年卫生部规章《血站管理办法（暂行）》将原料血浆的釆集和临床用血的釆集区分开来。这三个法律文件的制定已经考虑到临床用血的安全和保证血液制品的质量， 预防和控制经血液途径传播疾病的问题。这三个法律文件的主要内容是：一、国家实行无偿献血制度和单釆血浆统一规划、设置制度。二、卫生行政部门监督管理献血工作。 三、血站是不以营利为目的的公益性组织；血站实行执业许可证制度，血站技术工作人员实行考试合格证书制度，血站、采供血和检测原始记录实行10年保存制度。四、血站对献血者必须进行健康检查；医疗机构对临床用血必须进行核查……

第三句有部分有人翻译为：

As non-profit organizations, blood-stations have to be licensed and their employees have to be certified. The original records of blood sources, blood collection and distribution and blood tests are kept for 10 years.