在我的雅思教学生涯中，经常碰到学生上交的作业中出现这样的句子：Learning a new language is like learning to swim, it takes a lot of practice. 明眼人应该可以看出句子出现的问题，没错，就是“逗号连接两句话”！ 但是很多学生往往觉得这样的句子是没有错误，其中很大的原因可能是受到汉语表达方式的影响。
　　逗号连接两句话比比皆是。请看下面这个例子：
　　“孩子传统上从中学开始学习外语，但一些教育家建议可以更早开始学习。这一政策已经被一些教育当局或一些学校采用，结果有利有弊。支持这一政策的显而易见的论据是小孩子学语言与青少年相比容易得多。他们的大脑依然习惯于获取他们的母语，这有助于学习另一门语言，而且他们不像青少年，没有被自我意识约束。”
　　短短140个字就出现多处逗号连接两句话。深受这种思想“毒害”的小伙伴们在英文作文中犯这种错误也就不奇怪了。以上文中的“这一政策，结果有利有弊。”为例，同学们的翻译后的英文常常是这样的：
　　This policy has been adopted by some educational authorities or individual schools, the results are both advantages and disadvantages. y
　　这是一个非常典型的run-on sentence（连写句）。改正的方法往往有三种：
　　1.修改逗号为分号
　　修改后：
　　This policy has been adopted by some educational authorities or individual schools;the results are both advantages and disadvantages. t
　　2.添加并列连词（and, but, so, for）
　　修改后：
　　This policy has been adopted by some educational authorities or individual schools, andthe results are both advantages and disadvantages. t
　　3.添加从属连词或者介词
　　修改后：
　　This policy has been adopted by some educational authorities or individual schools, with both positive and negative outcomes. t
　　在搞清楚这种问题产生的原因和修改方式后，我们再来一起分析几个例子：
　　例子1：Computer lessons play an indispensable part in school curriculum, it provides students with opportunities to acquire skills and improve futures. y
　　错误分析：这句话犯了逗号连接两句的错误。经过分析，我们发现这两句话呈现因果逻辑关系。
　　改正：
　　a.Computer lessons play an indispensable part in school curriculum; it provides students with opportunities to acquire skills and improve futures. t（修改逗号为分号）
　　b.Computer lessons play an indispensable part in school curriculum, for it provides students with opportunities to acquire skills and improve futures. t（添加并列连词for）
　　c.Computer lessons play an indispensable part in school curriculum, as it provides students with opportunities to acquire skills and improve futures. t（添加从属连词as）
　　例子2：Prison is a kind of punishment, it has a certain deterrent effect to the lawbreakers. y
　　错误分析：这句话明显犯了逗号连接两句的错误。这句话乍一看不太好理解，经过分析，我们理清作者真正想表达的意思是“是公认的严厉惩罚，这个惩罚对潜在犯罪者有威慑作用。”所以除了添加连接词外，我们还微调了几处用词，使句子表意更鲜明！
　　改正： Prison is considered（被认为）a harsh（严厉的）punishment, which has a deterrent effect to would-be offenders（潜在罪犯）.