1. Grammar Level 4: Clauses
A clause is a group of words that contains a subject and its predicate. This one-two structure opens and closes an idea.
The complete clause contains not only its subject and predicate, but all of the modifiers and phrases that go with them. A sentence might consist of only one clause, or it might contain several clauses, each with its own subject and predicate.

2. Clauses
Example: In the following sentence, there are three clauses. In each clause, the subject/predicate set is underlined:
1. If the moon rises tonight,
2. I will get the telescope, and
3. you look through it.

3. Types of Clauses Two Kinds of Clauses
independent clause: an independent clause is a clause that makes sense independently. It can stand alone.
Example: You will yelp.
dependent clause: a dependent (or subordinate) clause is a clause that does not make sense unless it can “hang on to” an independent clause. It cannot stand alone.
Example: If you will yelp...

4. Adjective Dependent Clauses
An adjective clause) or relative clause is a dependent clause used as an adjective: a short (usually) dependent clause that follows a noun or pronoun and modifies it. An adjective clause often interrupts the main clause, dividing the subject and the verb. Adjective clauses begin with relative pronouns.
Example: The man who followed you turned left.
We watched the man who turned left.

5. Essential and Nonessential
Adjective clauses which are important to the meaning of the sentence need no commas around them. Adjective clauses which are unnecessary interruptions should be enclosed in commas.
If you need the clause, you don’t need the commas. If you don’t need the clause, you need the commas.
Example: The man who followed you turned left.
The man, who happened to know Humphrey, coughed.

6. That vs. Which
The relative pronoun that often indicates an essential adjective clause:
The book that you lost is on the shelf.
The relative pronoun which often indicates a nonessential adjective clause:
The book, which I enjoyed too, is on the shelf.

7. Adverb Dependent Clause
adverb dependent clause: Adverb clauses are dependent clauses that act as big adverbs. Adverb clauses usually begin with subordinating conjunctions.
Example: I jumped when the fish expanded.

8. Noun Dependent Clause
noun dependent clause: Noun clauses are dependent clauses which act as nouns. In the example below, the noun clause acts as a noun direct object to the action verb wish.
Example: I wish that I liked music

9. Placement of Dependent Clauses
Dependent clauses can not be used as sentences by themselves; they depend on independent clauses for meaning. The dependent clause may be placed before, after, or even in the middle of an independent clause.
If you find the crater, the expedition will be a success.
The empire will collapse when the thought-beam is destroyed.
The poet who wrote the anthem was exiled to Europa.
I found what I was looking for.

10. Clause vs. Sentence
the difference between a clause and a sentence: A clause has both a subject and a predicate, like a sentence, but a sentence always has a complete thought, whereas a clause might be incomplete.
A sentence can consist of several clauses:
If you find the dog, I will prepare its bath.

11. Four Sentence Structures
Key: I = independent clause
D = dependent clause
cc = coordinating conjunction
simple sentence: (Structure = I) A simple sentence is a sentence consisting of simply one independent clause. You can use a simple sentence to isolate an idea for attention.
Example: I have the sniffles.

12. Compound Sentence
compound sentence: (Structure = I + I or I + I + I, etc.) A compound sentence is a sentence compounded of two or more independent clauses. You can use a compound sentence to connect two related ideas of equal or nearly equal importance. Punctuate: I;I or I, cc I
Example:
The mutt went to Phoenix, but we came home.
George is a neurosurgeon; he specializes in brain surgery.

13. Complex Sentence
complex sentence: (Structure: I + D or D + I or D + I + D, etc.) A complex sentence is a sentence consisting of an independent clause joined to a dependent clause. You can use a complex sentence to show a primary idea which has a lesser idea in support of it. The independent clause will contain the primary idea. Punctuate: D, I or I, D.
Example: When the sun rises, we will depart.
We will depart when the sun rises.

14. Compound-Complex Sentence
compound-complex sentence: (Structure: I + I + D, or D + I + I, etc.) A compound-complex sentence is a sentence that contains both compound clause structure and complex clause structure. You can use a compound-complex sentence to employ the strategies of compound and complex sentences at once. Punctuate a compound-complex sentence two clauses at a time, according to the rules for compound and complex sentences.

15. Compound-Complex Sentence
Example:
We marched to Boston, and the legion slogged dejectedly when the surrender was signed.

16. Clause Punctuation
I, cc I (comma before coordination conjunction in compound sentence)
I; I (semicolon between clauses if no coordinate conjunction)
ID (no comma after independent clause in complex sentence)
D, I (comma after dependent clause in complex sentence)

17. Punctuation Errors
comma splice: A comma splice is the error of joining two independent clauses with a comma. (I,I)
Example: The mutt went to Phoenix, we went home.
Correct by inserting a coordinating conjunction after the comma, or change the comma to a semicolon.

18. Run-On Sentence
A run-on sentence is the error of joining two independent clauses with only a coordinating conjunction or with nothing. (IccI or II)
Example:
The mutt went to Phoenix but we went home. (needs a comma)
The mutt went to Phoenix we went home.

19. Four Types of Sentences
Declarative: A declarative sentence is a sentence that declares (states).
Example: I will.
Interrogative: An interrogative sentence is a sentence which interrogates (asks a question).
Example: Will you?

20. Four Types of Sentences
Imperative: An imperative sentence is a sentence which imperiously commands.
Example: Go away.
Exclamatory: An exclamatory sentence is a sentence which exclaims.
Example: I will!