托福寫作中標點符號的用法是許多考生在備考中都容易忽略的一個點，但有的時候標點符號對于句子的影響卻非常大，不慎用錯一個標點可能導致整句話意義都變了。下面，牛學君來給大家詳細解讀一下逗號在各種寫作句型中的用法。

托福寫作中逗號用法一

在并列連詞(and， but， for， nor， or， yet )前使用，用來連接句中的各分句。

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 break down of dead organic matter or from other living organisms.

托福寫作中逗號用法二

用逗號來分隔一系列單詞、詞組和從句。

Further more the walls of fungal cells are not made of cellulose， as those of plants are， but of another complex sugar like polymer called chitin， thematerial 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.

托福寫作中逗號用法三

逗號用來分隔與句子其他部分密切相連的簡短插入語或旁白。(較長的，更為突兀的或復雜的插入成分的則用破折號或圓括號。)

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

托福寫作中逗號用法四

在并列形容詞，即分別修飾同一個名詞的形容詞之間使用逗號，但也有的形容詞之間不加逗號的。

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

托福寫作中逗號用法五

用逗號來分隔非限定性修飾語，即該修飾語對于句子的意義并非必不可少。非限定性修飾語與限定性修飾語的區(qū)別在于，它即使被省略，也不會改變句子的主要意思。

(1) 同位語。

The canopy， the upper level of the trees in the rain forest， holds aplethora of climbing mammals of moderately large size， which may includemonkeys， cats， civets， and porcupines.

(2) 從句。

The canopy， the upper level of the trees in the rain forest， holds aplethora of climbing mammals of moderately large size， which may includemonkeys， cats， civets， and porcupines.

逗號在托福寫作中可以應用于多種句型中，很多同學在考試中不注意標點符號，或者亂點標點，這都是不可取的。希望大家能掌握標點的正確使用方法，在托福寫作考試中不要用錯。