句子是最大的独立语法单位：它以大写字母开头，以句号、问号或感叹号结尾。“句子”一词来源于拉丁语，意为“感觉”。该词的形容词形式为“句子”。该句传统上（但不充分）被定义为一个词或一组词，表达一个完整的想法，包括一个主语和一个动词。

句子结构类型

四种基本的句子结构是：

1. 简单句：只有一个独立从句的句子。
2. 复合句：两个（或多个）简单的句子，用连词或适当的标点符号连接起来。
3. 复合句：包含独立从句（或主句）和至少一个从属从句的句子。
4. 复合复合句：包含两个或多个独立从句和至少一个从属从句的句子。

句子的功能类型

• 陈述性：“衣服造就男人。裸体的人对社会几乎没有影响。”
• 疑问：“但是文学和新闻有什么区别？新闻是不可读的，而文学是不可读的。”（奥斯卡·王尔德）
• 命令：“阅读健康书籍时要小心。你可能会死于印刷错误。”（马克·吐温）
• 感叹词：“为一个想法而死；这无疑是高尚的。但如果人们为真实的想法而死，那该有多高尚啊！”

关于句子的定义和意见

“我试着用一句话，在一个上限和一个句号之间说出来。”

（威廉·福克纳在给马尔科姆·考利的信中）

"The term 'sentence' is widely used to refer to quite different types of unit. Grammatically, it is the highest unit and consists of one independent clause, or two or more related clauses. Orthographically and rhetorically, it is that unit which starts with a capital letter and ends with a full stop, question mark or exclamation mark." (Angela Downing, "English Grammar: A University Course," 2nd ed. Routledge, 2006)

“我对一个句子的定义是任何词语的组合，而不仅仅是一个意义对象的简单命名。”

（凯瑟琳·卡特·摩尔，“儿童的智力发展”，1896年）

"[A sentence is a] unit of speech constructed according to language-dependent rules, which is relatively complete and independent in respect to content, grammatical structure, and intonation." (Hadumo Bussmann, "Routledge Dictionary of Language and Linguistics." Trans. by Lee Forester et al. Routledge, 1996)

书面句子是向听者传达意思的一个词或一组词，可以回应，也可以是回应的一部分，并且带有标点符号

（Andrew S.Rothstein和Evelyn Rothstein，“有效的英语语法教学！”Corwin出版社，2009年）

"None of the usual definitions of a sentence really says much, but every sentence ought somehow to organize a pattern of thought, even if it does not always reduce that thought to bite-sized pieces." (Richard Lanham, "Revising Prose." Scribner's, 1979) "The sentence has been defined as the largest unit for which there are rules of grammar." (Christian Lehmann, "Theoretical Implications of Grammaticalization Phenomena," Published in "The Role of Theory in Language Description," ed. by William A. Foley. Mouton de Gruyter, 1993)

句子的概念定义

Sidney Greenbaum和Gerald Nelson在解释句子是什么和做什么时给出了不同的理解：

"It is sometimes said that a sentence expresses a complete thought. This is a notional definition: it defines a term by the notion or idea it conveys. The difficulty with this definition lies in fixing what is meant by a 'complete thought.' There are notices, for example, that seem to be complete in themselves but are not generally regarded as sentences: Exit, Danger, 50 mph speed limit...On the other hand, there are sentences that clearly consist of more than one thought. Here is one relatively simple example: This week marks the 300th anniversary of the publication of Sir Isaac Newton's Philosophiae Naturalis Principia Mathematica, a fundamental work for the whole of modern science and a key influence on the philosophy of the European Enlightenment. How many 'complete thoughts' are there in this sentence? We should at least recognize that the part after the comma introduces two additional points about Newton's book: (1) that it is a fundamental work for the whole of modern science, and (2) that it was a key influence on the philosophy of the European Enlightenment. Yet this example would be acknowledged by all as a single sentence, and it is written as a single sentence." (Sidney Greenbaum and Gerald Nelson, "An Introduction to English Grammar, 2nd ed." Pearson, 2002)

句子的另一种定义

D.J.Allerton提供了句子的另一种定义：

"Traditional attempts to define the sentence were generally either psychological or logical-analytic in nature: the former type spoke of 'a complete thought' or some other inaccessible psychological phenomenon; the latter type, following Aristotle, expected to find every sentence made up of a logical subject and logical predicate, units that themselves rely on the sentence for their definition. A more fruitful approach is that of [Otto] Jespersen (1924: 307), who suggests testing the completeness and independence of a sentence, by assessing its potential for standing alone, as a complete utterance." (D. J. Allerton. "Essentials of Grammatical Theory." Routledge, 1979)

句子的两部分定义

Stanley Fish认为一句话只能分为两部分：

"A sentence is a structure of logical relationships. In its bare form, this proposition is hardly edifying, which is why I immediately supplement it with a simple exercise. 'Here,' I say, 'are five words randomly chosen; turn them into a sentence.' (The first time I did this the words were coffee, should, book, garbage and quickly.) In no time at all I am presented with 20 sentences, all perfectly coherent and all quite different. Then comes the hard part. 'What is it,' I ask, 'that you did? What did it take to turn a random list of words into a sentence?' A lot of fumbling and stumbling and false starts follow, but finally someone says, 'I put the words into a relationship with one another.'...Well, my bottom line can be summarized in two statements: (1) a sentence is an organization of items in the world; and (2) a sentence is a structure of logical relationships." (Stanley Fish, "Devoid of Content." The New York Times, May 31, 2005. Also "How to Write a Sentence and How to Read One." HarperCollins, 2011)

句子较轻的一面

有些作家对一句话有幽默的看法：

"One day the Nouns were clustered in the street. An adjective walked by, with her dark beauty. The Nouns were struck, moved, changed. The next day a Verb drove up, and created the Sentence..." (Kenneth Koch, "Permanently." Published in "The Collected Poems of Kenneth Koch." Borzoi Books, 2005)