Course Content
Chapter 3: Writing Mechanics Help
Chapter 12: Teaching Writing
Chapter 23: Teaching Reading
College English Composition: Help and Review
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Structure of Sentences

The purpose of sentences is to help make communication effective. Imagine if someone said this sentence to you: ‘Milk to later I some going the am get store to.’ Does that make any sense? Of course not! That is because that sentence has no sentence structure, or the rules and guidelines for building sentences.

Put those words in the proper place and you get, ‘I am going to the store to get some milk later,’ which is a clear and effective message. Sentence structure is very important in order for our speech and our writing to be useful. There are numerous concepts that factor into sentence structure. In this lesson, we’ll look at only three of those concepts and how to avoid any errors.


The first area that can affect sentence structure is comparison. In the broad sense of the word, comparison in grammar refers to showing similarities or differences in degree between two objects or ideas. Structurally, when making comparisons, you must follow a specific format in order for your message to be clear.

The two main forms of comparison are comparative and superlative. You need to know that comparative deals with comparing only two objects or ideas, whereas superlative compares three or more. Structurally, when using the comparative, you need to attach the suffix ‘er,’ and for superlative, attach the suffix ‘est.’ For example, let’s say you wanted to compare the height of two trees. Since you have only two objects, then you use the comparative form.

‘The oak tree is taller than the ash tree.’ The adjective, ‘tall,’ has the suffix ‘er’ to show that the two objects are being compared to each other. Now think of how you would state the idea that the oak tree has the most height compared to all the other trees in that forest. ‘The oak tree is the tallest tree in the forest.’ The superlative suffix is now added to the adjective ‘tall’ to indicate multiple trees are being compared.

One thing to note when discussing comparative and superlative is what to do when adjectives have more than two syllables. Does it sound correct to say, ‘This dress is beautifuller than your dress’? Of course not! This is because the adjective ‘beautiful’ has more than two syllables. In this case, you add the word ‘more’ before the adjective. ‘This dress is more beautiful than your dress.’ For the superlative, you add the word ‘most.’ ‘This dress is the most beautiful.’ However, be sure to remember to never use the words ‘more’ and ‘most’ in addition to the suffixes ‘er’ or ‘est.’ That would be superfluous and should be avoided at all times.

Overall, looking closely at how you are comparing objects or ideas is very important to your communications. Imagine if you were reading a textbook that used phrases like ‘most beautifullest,’ or ‘The oak tree is tallest than the ash tree.’ You would immediately begin to doubt the content of the entire text just because it made these simple comparative mistakes. In your own work, check to see how many objects or ideas you are comparing and how many syllables are in the comparing words. This will help you avoid making any errors when using comparison.


Once you have checked your writing for comparison errors, you need to be sure to pay attention to parallelism. Within grammar, parallelism means that all parts or words in a sentence have the same form.

Let’s look at an example to clarify how this works in sentence structure. Look at this sentence: ‘Tomorrow I will go skiing, snowboarding and hike.’ Did you notice something was a bit off? Look at the structure of the listed activities: ‘skiing,’ ‘snowboarding,’ hike.’ Which one doesn’t fit? ‘Skiing’ and ‘snowboarding’ are parallel because they both have the same ‘ing’ ending. ‘Hike’ is in a different form and is not parallel. To make it parallel, ‘hike’ must be changed to ‘hiking.’

Let’s look at one more example to show parallelism. ‘Today I went to the store, drive my mother to the doctor’s, and ran two miles.’ Did you see which word was not parallel? What tense are the verbs? ‘Went’ and ‘ran’ are in the past tense, but ‘drive’ is in present. This is not parallel. ‘Drive’ needs to be changed to ‘drove’ in order to make this sentence parallel.

When checking for parallel structure, be sure to look at verb tense. All your actions should be in the same form. However, don’t think parallelism only refers to verbs. This structure should also be followed when listing nouns and adjectives. If you have a list of nouns, don’t throw a verb in there. If you have a list of adjectives, you cannot include a noun. Check your writing to make sure your sentence follows a parallel structure.


The final concept dealing with sentence structure we will look at is correlation. Correlation is very similar to parallelism. Basically, correlation refers to using words that come in pairs, or correlate with each other. The most common correlating pairs are either/or, neither/nor, both/and, not only/but also. When you use one word of the pair, the second must be used later in the sentence.

Look at these sentences as examples:

  • ‘They either drove or took a cab.’
  • ‘The teacher not only gave homework, but also assigned a project.’
  • ‘I forgot both my science project and my English paper.’
  • ‘Neither the rain nor the sleet will stop the mailman from doing his job.’

Check your writing for these correlating pairs of words. Be sure to not only use the correct pairing, but to include the second word of the pair. For example, the most common error occurs with the not only/but also pair. Many people will leave out the word ‘also,’ making the sentence read, ‘The teacher not only gave homework, but assigned a project.’ This might sound fine verbally, but grammatically you need the correlating word ‘also’ to relate back to the word ‘only.’

Lesson Summary

To review, sentence structure refers to the rules and guidelines for building sentences. There are many concepts under those rules and guidelines, but three important ones are comparison, correlation and parallelism.

Comparison refers to comparing different objects or ideas. When doing so, you need to pay attention to how many objects you are comparing. If only two, then use the comparative suffix ‘er’ or the word ‘more.’ When three or more objects are being compared, use the superlative suffix ‘est’ or the word ‘most.’ Never use both the suffix and ‘more’ or ‘most’ at the same time.

The second concept is parallelism, which means following a consistent form to the words in sentences. If you have a list of verbs, then you cannot add a noun. If you have a list of nouns, then you cannot add an adjective. Last, you must also make sure the list is all in the same form. If all your verbs are in past tense, then make sure none are in the present tense. If all your nouns are plural, do not add in a singular one. Keeping your words consistent will help make your writing clear and effective.

Correlation refers to certain words that must be used together. The most common correlating pairs are either/or, neither/nor, both/and, not only/but also. When using these, double check that you used the correct word with its pair and that you did not leave any part of the correlation out.

Follow these guidelines and you will be sure to have useful and successful sentence structure.

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