Sentence Building

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English has two basic ways of combining words into groups: phrases and clauses.

  • Phrases are centred around nouns (in the van, by early morning).
  • Clauses are centred around verbs (she runs the marathon; when he saw the ruins).
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Types of ClausesCombining Clauses

Types of Clauses

All sentences are constructed from two types of clauses.

  1. The main, principal, or independent clause. It contains a subject (noun), a predicate (verb), and expresses a complete thought:

She decided to walk to the park.

(subject)          (verb)              (= complete thought)

  1. The subordinate or dependent It also contains a subject and a verb but does not express a complete thought. Subordinate clauses often begin with words like since, while, although, despite, etc.:

Because it was a sunny day

(subject)           (verb)              (= incomplete thought)

Combining Clauses

Combining a Subordinate and a Main Clause

Combining a Subordinate and a Main Clause

Combining clauses is what sentence building is all about. Joining a subordinate clause with a main clause requires only a comma:

Because it was a sunny day, she decided to walk to the park.

(subordinate)                           (main)

Combining Two Main Clauses

Combining Two Main Clauses

The tricky part comes when two main clauses are joined together. Punctuation options include:

A period: It was a sunny day. She decided to walk to the park.

A semi-colon: It was a sunny day; she decided to walk to the park.

A comma with a linking word (coordinating conjunction): It was a sunny day, so she decided walk to the park.

Other coordinating conjunctions are and, but, yet, or, nor and for.

✘ Comma splices: Do not use a comma to join two main clauses in a sentence: e.g., It was a sunny day, she decided walk to the park. A comma is too weak a form of punctuation, and the resulting error is called a comma splice.

✘ Run-on sentence: Joining two main clauses with no punctuation is called a run-on sentence.

Both are considered to be major sentence errors.

A special case is when two main clauses are combined, and the second one begins with however (or other conjunctive adverbs like therefore, thus or nevertheless). A semi-colon must be used; a comma is too weak, and will create a comma splice:

It was raining; however, she decided to walk to the park.

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