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Basic Grammar and Punctuation: Compound Sentences

The tutorials below address basic grammar and punctuation errors writers routinely have. Use these guidelines to proofread and correct errors in your papers before submission. For hands-on help, see a tutor in your campus Learning Support Commons.

About Compound Sentences

Once you can identify a basic sentence, you can join or separate your sentences to best communicate your ideas.

 

A compound sentence joins two or more sentences that have related ideas of equal importance. The two sentences go together. Each sentence or independent clause must still have a subject and a verb.

 

For example:

 

She wanted spinach salad; he wanted a hamburger.

He went to the party, but she stayed home.

 

One way to create a compound sentence is with a semi-colon.

Not a common practice, a semi-colon is used only where ideas are very closely related.

 

For example:

 

She loves me; she loves me not.

They say it's your birthday; it's my birthday too! - Paul McCartney

Management is doing things right; leadership is doing the right things. - Peter Drucker

 

Another way to create a compound sentence is with a coordinating conjunction.

Coordinating conjunctions are sometimes referred to as FANBOYS. Notice how a comma is used with a coordinating conjunction.

 

For – He couldn't go home, for he had no place to go. 

And – I took a taxi, and she drove home.

Nor – He didn't want help, nor did she offer it.

But – I wanted to go late, but she wanted to go on time.

Or – She cooked dinner, or she went out to a restaurant.

Yet – She owned a car, yet she didn't know how to drive it.

So – She had to go, so she called a friend to drive her.

 

Common problems with compound sentences include commas splices.

A comma alone is not enough to connect two sentences.

For example:

 

Wrong – I was tired from working late, I had to go to class anyway.

Right – I was tired from working late; I had to go to class anyway.

Right – I was tired from working late, but I had to go to class anyway.

 

Common problems with compound sentences include fused sentences.

Sentences cannot just run together. They must be joined with a semi-colon or a coordinating conjunction.

 

For example:

 

Wrong – My brother just graduated from high school he will attend St. Petersburg College.

Right – My brother just graduated from high school; he will attend St. Petersburg College.

Right – My brother just graduated from high school, so he will attend St. Petersburg College.

 

 

Dual construction vs. the coordinating conjunction - or when to use the comma!

When combining sentences into a compound sentence, you need a comma before the coordinating conjunction.

For example:

 

I like peanut butter, and I like jelly.

He eats macaroni, but he won't eat cheese.

 

BUT when combining two nouns or verbs, you don't need a comma.

 

I like peanut butter and jelly.

He eats macaroni or cheese but not both.

 

 

A special use of semi-colons - the Conjunctive Adverb

Sometimes mistaken for a FANBOY, a conjunctive adverb actually joins two sentences with a semi-colon AND has additional punctuation inside the second sentence.

 

For example:

 

I hate spinach; however, I love broccoli.

I want to graduate with honors; furthermore, I want to go to law school.

I don't want to go out tonight; besides, I have homework to do.

 

 Some common conjunctive adverbs include accordingly, also, however, furthermore, nevertheless, consequently, finally, likewise, and meanwhile.