Introduction

在之前学习英语的过程中，经常将 clause 翻译为“从句”，但其实这是非常不准确的。 Clause 的定义是：

Clause

A clause is a group of words that contains a subject and a verb that have a relationship. This relationship is crucial; a clause conveys information about what that subject is or is doing, rather than simply being a random grouping of words.

The only defining characteristic of a clause is that it must contain a related subject and verb.

只要包含主语和动词一组词，并且主语与动词之间存在着关系，那么这组词就是一个 clause。因此，clause 本身并不包含“从”的意思，翻译成“子句”比较恰当。

Clause 是在 phrase 和 sentence 之间的一个定义：

When it comes to expressing a complete thought, a clause falls between a phrase and a sentence.

phrase: A phrase is a small group of words that communicates a concept but isn’t a full sentence.

sentence: At its core, a sentence is a string of words used to express a complete thought. There’s a lot of flexibility about what constitutes a sentence, but the central rule is that it must contain both a subject and a verb.

在很多情况下，clause 本身就可以作为一个 sentence，但是 phrase 不可以。下面的例子展示了 phrase 和 clause 之间的区别：

• Meows so loudly (phrase)
• That cat meows so loudly (clause)

在上面的例子中，clause 就是一个 independent sentence。除此之外，它还可以作为 complex sentence 的一部分。例如：

• That cat meows so loudly when she wants to eat.

Three distinct functions

在英语中，Clause 有三种不同的功能：充当 adverbs，adjectives，或者 nouns。如果 dependent clause 在 sentences 中充当副词，那么它就是副词性子句；如果充当形容词，就是形容词性子句；如果充当名词，就是名词性子句。

• The pool was installed after they built the deck. (adverb clause)
• My friend who rides a motorcycle said it’s a great weekend to ride. (adjective clause)
• She completely understood everything he said. (noun clause)

Types of clauses

Independent clauses

Independent clause 是指那些能够独立成句的子句，也称为 simple sentence.

An independent clause is a clause that can stand on its own as a distinct sentence.

例如：

• I love eating cookies.
• My dog barks a lot.

一般而言，Independent clause 都不长，有别于 complex sentences，但它们可以作为 complex sentences 的一部分。

实际上，除了 complex sentences，其他结构的句子，例如 compound sentences 和 compound-complex sentences，都是通过结合 independent clauses 和 dependent clauses 构成的。

Dependent clauses

Dependent clause （也被称为 subordinate clauses，即从句）不是一个完整的句子，Dependent clause 必须依赖于independent clauses 才能清楚地表达出观点。

subordinate clauses: A subordinate clause is a clause that cannot stand alone as a complete sentence; it merely complements a sentence’s main clause, thereby adding to the whole unit of meaning. Because a subordinate clause is dependent upon a main clause to be meaningful, it is also referred to as a dependent clause.

例如：

• When I grow up
• Although he sings well
• The mouse that was hiding

这些句子都不是完整的句子。为了使上面的句子成为完整的句子，我们需要将它们和 independent clauses 相结合：

• When I grow up, I want to be a doctor.
• Although he sings well, he hates karaoke.
• I searched through the basement and found the mouse that was hiding.

在前两个例子中，dependent clause 在 independent clause 前，并使用逗号分割。因此我们在写作的时候要记住：Whenever the dependent clause comes first in a complex sentence, it’s followed by a comma.

Clauses combination

在英语中，所有的句子都至少包含一个 independent clause。在很多时候，我们需要将多个 clause 结合起来，构成一个完整的句子：

Every sentence you write includes at least one independent clause. The other clauses in your sentence determine how you can combine them with your independent clause.

根据句子结构的不同，句子可以分为 compound sentences，complex sentences 和 compound-complex sentences.

Compound sentences

Compound sentence（复合句）的定义：

A sentence that includes two or more independent clauses is known as a compound sentence.

Compound sentences 中的 independent clauses 可以通过以下三种方式进行连接：

• I love drinking soda, but I know it’s bad for my teeth. (by a comma paired with a coordinating conjunction)
• Maria loved hosting dinner parties; her friends enjoyed her cooking. (by a semicolon)
• We danced until the band finished playing: they played until midnight. (by a colon)

这种多个 independent clauses 结合的方式被称为 coordination（并列）.

当所有的 clauses 都是 independent clauses 时，可以使用 coordinating conjunction （并列连接词）进行连接。英语中的 coordinating conjunction 可以用缩写 FANBOYS 来记忆：for, and, nor, but, or, yet, so。

Complex setences and compound-complex sentences

Complex sentence（复杂句）和 compound-complex sentence 的定义：

A sentence that includes an independent clause and one or more dependent clauses is known as a complex sentence, and a sentence that includes two or more independent clauses and at least one dependent clause is known as a compound-complex sentence.

在这些句子中，我们需要使用 subordinating conjunction（从属连接词） 将 independent clause 与 dependent clause 结合。Subordinating conjunctions 的数量比 coordinating conjunctions 多得多，可以根据它们的功能对它们进行分类。

在 complex sentences 和 compound-complex sentence 中，subordinating conjunction 象征着 dependent clause 的开始，例如：

• The fun can begin now that the clown is here.
• The pool is open daily until the temperature drops.
• While we slept, the plane reached its destination.
• Before you leave, remember to take a goodie bag!

我们可以看到，当 dependent clause 出现在句子前面时，我们需要在其后面添加一个逗号。

Subordinating conjunctions 并不是向句子中添加 dependent clause 结构唯一的方式，我们还可以使用 relative pronouns 或者 relative adverbs 引导 dependent clauses.

Relative pronouns 包括：that，whose，whom，who，和 which. 例如：

• The guy who shouted all night made it impossible to fall asleep.
• Pac’s, that restaurant with the arcade, is the best restaurant in town.

Relative adverbs 包括 where，when，how，和 why. 例如：

• The traffic jam is the reason why we were late.
• I have no idea when my hose stopped working.

References

[1] Clauses: How Do We Use Them in English? - Grammarly Blog.

[2] All the Common Types of Sentences, Explained - Grammarly.