Academic writing has different features that separate it from other types of composition, and complex grammar is one of these essential aspects. Considering that there are many grammatical rules to remember, it is important to keep the most common grammatical mistakes in mind that make writing confusing.

Most often, mistakes occur in sentence structures. First of all, to help you understand these mistakes clearly, let’s cover basic grammatical terms:

  • A sentence may contain dependent and independent
  • An independent clause contains

a subject and a verb (predicate) and can

stand alone as a sentence.

This book was interesting.

In this sentence, the subject is ‘this book,’ and the verb is ‘was.’

A complete sentence should have at least one independent clause.

  • A dependent clause contains a subjectand a verb, but it does not express

a complete idea and cannot stand alone as a sentence.

Although they visited this place…

This dependent clause has an unfin- ished statement, so it cannot stand alone without an independent clause.

Dependent clauses begin with subordi- nating conjunctions such as while, although, because, after, when, while,

if, unless, etc.

After briefly covering the main clauses, let’s take a look at the common mistakes in sentence structuring.

Errors in sentence structuring

  • A sentence fragment (or incomplete sentence) is an unfinished statement, often consisting of only a dependent


Other examples of incomplete sentences are sentences that lack a subject or predicate.


  • Since they have not finished their studies.
  • Important facts about obesity.


  • Since they have not finished their studies, they had to apply to low-paying jobs.
  • Important facts about obesity are presented in this article.

The incorrect use of prepositions

is self-explanatory. Prepositions are words before nouns, pronouns, and noun phrases which, in most cases, serve to indicate location and time. Here are some examples of misused prepositions:

  • to result in reason for on a website
  • to have an impact on, but the verb ‘to impact’ is used without a preposition
  • to put emphasis on something, but the verb ‘to emphasize’ is usually used without a preposition

Although there are a few rules for preposition usage, they are mostly used in fixed expressions, and therefore, the best way to learn prepositions is to memorize the phrases in  which  they are used.

Below are links to helpful websites that list the most common prepositions:

The incorrect use of articles

is also a common mistake in writing. Articles stand before nouns, and they are used to show whether the noun is general or specific. Using articles in English can be tricky, so it is important to memorize the main rules of article usage.

Below are links to helpful websites that describe these rules:


Misused semicolons.

Use a semicolon:

  • To separate sentences where the conjunction has been left out.
  • The story is exciting; the author managed
  • to describe the events well.
  • Before words such as however, therefore, thus, for example when they introduce a complete sentence (independent clause).
  • The topic is difficult to understand; however, the writer explains it clearly.

Do not confuse a colon (two vertical dots) with a semicolon (a comma with a dot).

  • Use a colon after a complete sentence to introduce a list of items (not
  • a semicolon!)
  • An essay contains different sections:
  • an introduction, body, and a conclusion.
  • Do not use a colon after a complete sentence after phrases such as ‘for example’ and ‘includes’ because these words already indicate an introduction of an example:


  • An essay includes: an introduction, body, and conclusion.


  • An essay includes an introduction, body, and conclusion.

An incorrect parallel structure

occurs in a sentence that does not contain a repetition of the same grammatical forms:


  • I want to study in this college and working in this field.


  • I want to study in this college and to work in this field.