英語句型看似複雜多變，其實源於兩大鑽石句型，即：①主語+謂語+賓語(S+V+O);②主語+系動詞+表語(S+V+P) (注：本句型總共有4種形式，分別因謂語動詞的不同特點而決定謂語之後有無賓語或補足語，具體為：主語+謂語、主語+謂語+賓語、主語+謂語+間接賓語+直接賓語、主語+謂語+賓語+賓語補足語，為了簡明扼要的說明問題，故將其總結為一種句型“主語+謂語+賓語”)。
每一成分皆可複雜化，由此加大了句子的理解難度。下面就演示一下這兩大基本句型是如何擴充套件成複雜的長難句的。
一、句子擴充套件：修飾成分加長
(一)鑽石句型①主謂賓句型
The boy (主語) likes (謂語) English (賓語).
1.主語擴充套件：
The clever boy likes English.
The boy with a book in his hand likes English.
The boy who is full of imagination likes English.
The clever boy who is full of imagination with a book in his hand likes English.
注：主語中心詞為the boy, 可以通過加形容詞、介詞短語、定語從句及其組合等成分使主語複雜化，從而增加理解難度。考研翻譯中的`主語考點多為修飾成分繁多的主語。
2.謂語擴充套件：
The boy likes English very much.
The boy likes English out of interest.
The boy likes English influenced by his parents.
The boy likes English, hoping that one day he can go abroad.
The boy liked English when he was five years old.
注：謂語動詞like通過新增副詞短語、介詞短語、現在分詞短語、過去分詞短語、狀語從句等進行擴充套件，從而使句子變得複雜，增加了理解難度。考研翻譯中注意找準動詞及其修飾成分,以弄清邏輯關係。
3.賓語擴充套件：
The boy likes American English.
The boy likes English, the international language.
The boy likes English which is the most widely spoken language in the world.
The boy likes English spoken by many people nowadays.
The boy likes English, a beautiful language, spoken by many people living in every corner of the world.
注：賓語English通過新增形容詞(短語)、同位語、定語從句、分詞短語及其組合進行擴充套件，從而使簡單句變得複雜化。考研翻譯中要注意這些修飾成分，如分詞結構要找出邏輯主語等，定語從句要找出先行詞，等等。
(二)鑽石句型②主系表句型
The girl (主語) is (系動詞) Mary (表語).
各部分擴充套件：
The girl in a pink hat with a book in her hand is probably Mary a kind-hearted girl of inexhaustible energy which often amazes her classmates.
注：此句的擴充套件同上(也是通過新增修飾成分變複雜)，不再贅述。
二、句子擴充套件：成分替換
句子的複雜不僅體現在修飾成分繁多上，還體現在句子成分本身的複雜化上，下面就通過句子成分由簡單到複雜的替換來演示句子是如何變難的。
