英语句型看似复杂多变，其实源于两大钻石句型，即：①主语+谓语+宾语(S+V+O)和②主语+系动词+表语(S+V+P)(注：本句型总共有4种形式，分别因谓语动词的不同特点而决定谓语之后有无宾语或补足语，具体为：主语+谓语、主语+谓语+宾语、主语+谓语+间接宾语+直接宾语、主语+谓语+宾语+宾语补足语，为了简明扼要的说明问题，故将其总结为一种句型“主语+谓语+宾语”)。每一成分皆可复杂化，由此加大了句子的理解难度。下面就演示一下这两大基本句型是如何扩展成复杂的长难句的。
一、句子扩展：修饰成分加长
(一)钻石句型①主谓宾句型
The boy (主语) likes (谓语) English (宾语).
1.主语扩展：
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：主语中心词为the boy, 可以通过加形容词、介词短语、定语从句及其组合等成分使主语复杂化，从而增加理解难度。考研翻译中的主语考点多为修饰成分繁多的主语。
2.谓语扩展：
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：谓语动词like通过添加副词短语、介词短语、现在分词短语、过去分词短语、状语从句等进行扩展，从而使句子变得复杂，增加了理解难度。考研翻译中注意找准动词及其修饰成分,以弄清逻辑关系。
3.宾语扩展：
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：宾语English通过添加形容词(短语)、同位语、定语从句、分词短语及其组合进行扩展，从而使简单句变得复杂化。考研翻译中要注意这些修饰成分，如分词结构要找出逻辑主语等，定语从句要找出先行词，等等。
(二)钻石句型②主系表句型
The girl (主语) is (系动词) Mary (表语).
各部分扩展：
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：此句的扩展同上(也是通过添加修饰成分变复杂)，不再赘述。
