托福写作中如何正确使用逗号

很多托福考生会在自己的托福写作运用大量逗号，甚至会一逗到底，其实这是错误的。英语的句式结构要求比较严格，如果逗号使用不当，很有可能就造成语法错误，拉低托福写作的分数。今天，就告诉托福考生们如何在托福写作中正确使用逗号。

【用逗号来分隔一系列单词、词组和从句】

Furthermore the walls of fungal cells are not made of cellulose, as those of plants are, but of another complex sugar like polymer called chitin, the material from which the hard outer skeletons of shrimps, spiders, and insects are made.

They are a major cause of structural damage to building timbers, a cause of disease in animals and humans, and one of the greatest causes of agricultural losses.

【在并列形容词，即分别修饰同一个名词的形容词之间使用逗号，但也有的形容词之间不加逗号的】

For men, heroism was usually described as bravery and the active, successful lover coming of adversity.

【在以"月、日、年"为次序排列的日期间使用逗号。如果这种次序的日期出现在句子中间，则在"年"后也加上逗号】

Martin Luther King, Jr., was born on January 15, 1929, and died on April 4, 1968.

但在以"日、月、年"为次序排列的日期间，不使用逗号。

Martin Luther King, Jr., was born on 15 January 1929, and died on 4April 1968.

在"月"和"年"之间，或"季节"和"年"之间，不使用逗号。

The events of July 1789 are as familiar to the French as those of July 1776 are to Americans.

发生在1789年7月的那些事件对于法国人来说，就像美国人对于发生在1776年7月的那些时间一样熟悉。

【托福写作中表示地名时】

Pandas come from China, Asia.

【在并列连词(and, but, for, nor, or, yet )前使用，用来连接句中的各分句】

The principal reason for this is that none of them possesses chlorophyll, and since they cannot synthesize their own carbohydrates, they obtain their supplies either from the breakdown of dead organic matter or from other living organisms.

【逗号用来分隔与句子其他部分密切相连的简短插入语或旁白。较长的，更为突兀的或复杂的插入成分的则用破折号或圆括号】

Chemical fertilization, for example, helps to produce better crops, but is harmful to the environment.

【用逗号来分隔非限定性修饰语，即该修饰语对于句子的意义并非必不可少。非限定性修饰语与限定性修饰语的区别在于，它即使被省略，也不会改变句子的主要意思】