句式就是句子的結構方式，也就是句子的式樣或格式。不同的思想內容要用不同的句式來表達；而同一思想內容也可以用不同的句式來表達。句式不同，表達效果也就不同。只有句式多樣化，文章纔會生動有趣，充滿活力。可是，在實際寫作中，初學寫作的學生往往一篇文章都是千篇一律的`簡單句，文章單調乏味，毫無生氣。筆者認爲，恰當地使用某些方法或手段有助於實際表達形式的多樣化，增強表達效果。茲將常用方法簡單介紹如下。
改變句子的開頭
許多學生在寫作中傾向於用與人有關係的詞性，用名詞和代詞作爲句子的開頭，如 People，We，I，He，They，She等。但這種開頭見多了，難免讓人厭倦。試比較：
A．People throughout the country have greatly demanded all kinds of nutritious food．
B．There is a great demand across the country for all kinds of nutritious food．
第一句改用非人稱名詞作爲主語開頭，第二句則用there ＋be句型開頭。這樣既改變了主語＋謂語＋賓語單調句型，又把想強調的意思突出出來。實際上，爲了把文章寫得生動活潑，除了用主語開頭外，還可以用句子的其他成分開頭。
1．用副詞開頭
Too often，students stray into the habit of cheating on tests．
2．用同位語開頭
Air，water and oxygen，everything that is necessary for life．
3．用狀語開頭
Dark and empty，the house looked very different from the way I remembered it．
4．用表語開頭
Equally essential to the highest success in learning a language are intense interest plus persistent effort．
5．用賓語開頭
My advice you would not listen to；my helps you laughed at．Now you will have what you asked for．
6．以短語修飾語開頭
1）以介詞短語開頭
To me the news was very interesting，but to my wife very boring．
2）以分詞短語開頭
Disturbed by the discord of American life in recent decades，Menchester took flight for the pacific islands．
3）以不定式短語開頭
To pass the exam，you should work very hard．
二、巧用連接詞
有的學生在作文中使用過多簡單句，成了簡單句堆砌；有的寫複雜句時，動輒用so， and，then，but，or，however，yet等非但達不到豐富表達方式的目的，反而使句子結構鬆散、呆板。爲了避免這種現象，可以透過使用連接詞，尤其是一些表示從屬關係的連接詞，如 who，which，that，because，since，although，after，as，before，when，whenever，if，unless，as if等，不僅能夠豐富句型，而且還能夠把思想表達得更清楚，意義更連貫。例如：
Natural resources are very limited．They will be exhausted in the near future．It is not true．But it becomes a major concern around the world．This is a widely accepted fact．
這段文字用簡單句表達，它們之間內在的邏輯關係含糊不清，意思支離破碎。如果使用連接詞，將單句與其前後合併，形成主次關係，就把一個比較複雜的內容和關係表達得層次清楚、結構嚴謹。例如：
It is a widely accepted fact that there is a major concern around the world for the exhaustion of limited natural resources in the near future，though it is unlikely to be true．
再如：
The Mississippi River is one of the longest rivers in the world，and in spring time it often overflows its banks，and the lives of many people are endangered．
此句用and把三個分句一貫到底，既乏味又可笑。如果使用了關係代詞which，語義就會更連貫，語言也會更流暢：
The Mississippi River，which is one of the longest rivers in the world，often overflows its banks in the spring time，endangering the lives of many people．