句子可长可短，同一件事，可以用不同的句式表达。如果句子清一色是简单句，文章必定很单调乏味。如果全篇充满了冗长的复杂句，读起来也很费力。最好的方法是以简单句为基础，配合适当的并列句和复杂句。简单句可长可短，通常要加些附属成分，如分词短语、介词短语、副词短语、不定式动词短语，以及节缩成分。
总之，作者可根据情况，使句子多样化，使文章灵活多姿。例如下列五个句子的基本概念一样，但是句式不同，内容重点也有些差别：
(1) The goats grazed peacefully in the farm and were unaware of the approaching hunter. (并列分句(1)+2)
(2) Grazing peacefully, the goats in the farm were unaware of the approaching hunter. (现在分语短语+简单句)
(3) In the farm, the goats grazed peacefully and were unaware of the approaching hunter. (副词短语+并列分句(1)-(2) )
(4) There were goats grazing peacefully in the farm, unaware of the approaching hunter. (简单句+形容语短语)
(5) As the goats grazed peacefully in the farm, they were unaware of the approaching hunter. (原因副词从句+主句)
(1)和(5)的句式最常见；如果加上其他三种互相交替，句子不是更多样化吗？
最后，看看这两个句子要如何多样化呢？
(6) The young pilot was on his first overseas training.
(7) He felt very uneasy.
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(a) The young pilot on his first overseas training felt very uneasy.
(b) The young pilot felt very uneasy during his first overseas training.
(c) The young pilot`s first overseas training made him feel very uneasy.
(d) Extreme uneasiness seized the young pilot on his first overseas training.
(e) The young pilot was on his first overseas training, feeling very uneasy.
(f) It being his first overseas training, the young pilot felt very uneasy.
(g) Being on his first overseas training, the young pilot felt very uneasy.
(h) The young pilot was on his first overseas training and felt very uneasy.
(i) The young pilot, who was on his first overseas training, felt very uneasy.
(j) When the young pilot was on his/first overseas trainging, he felt very uneasy.
(k) As the young pilot was on his first overseas training, he felt very uneasy.
(l) The young pilot was on his first overseas training, so that he felt very uneasy.
在上述12个句子中，(a)-(g)是简单句；(h)是并列句；(i)-(l)是复杂句。简单句除(b)和(g)之外，其他五样，用的人并不多。人们最喜欢采用复杂句，尤其是(j)和(k)这两款；接着便是并列句(h)。如果大多数人的句子只限于(b),(g), (h), (j)和(k)这五种，而其他的则弃如敝屣，不是很可惜吗？