HESI A2 Grammar common mistakes
HESI A2 Grammar · Understand the traps and how to avoid them.
Choosing the pronoun by how formal it sounds rather than by its grammatical role, so a candidate writes 'between you and I' or 'for my sister and I' because 'I' feels more correct than 'me'.
Writers are often corrected for using 'me' as a subject ('me and my friend went'), and they overgeneralize that correction to every position, including after prepositions and in compound objects where the objective case is required.
What to do instead
Strip the sentence to the pronoun alone and test it: 'between I' versus 'between me' immediately sounds wrong, and 'for I' versus 'for me' resolves the compound. Apply the same deletion test to subject compounds ('He and I went' versus 'Him and me went'). Build a short list of prepositions that take the objective case (between, for, with, to, from, at, by) and recite the compound after each one aloud.
Matching a verb to the nearest noun instead of to the true subject when a prepositional phrase or parenthetical sits between them, producing 'The box of files were on the desk' or 'Each of the students have a book'.
The ear latches onto the last noun it hears, and long interrupting phrases push the real subject far enough away that proximity overrides agreement. Indefinite pronouns like each, either, neither, everyone, and everybody are also singular but feel plural because they refer to groups.
What to do instead
Cross out every prepositional phrase between the subject and verb before deciding, then read the skeleton aloud ('The box were' becomes obviously wrong). Memorize the singular indefinite pronouns as a fixed list (each, either, neither, one, everyone, everybody, someone, nobody, anyone) and the plural-only ones (both, few, many, several). For 'either...or' and 'neither...nor', agree with the nearer subject, and note that 'there is/are' agrees with the noun that follows the verb.
Leaving a sentence fragment or joining two independent clauses with only a comma, often because the candidate judges a sentence by its length rather than by whether it contains a subject and a finite verb.
Long sentences feel complete and short ones feel incomplete, so a lengthy subordinate clause starting with 'Because' or 'Although' passes as a sentence, while two short complete thoughts joined by a comma pass as one. The candidate is not checking for the structural markers.
What to do instead
For every sentence, locate the main subject and its verb and confirm the group can stand alone; a clause beginning with because, although, when, if, since, or which cannot. For comma splices, apply one of four repairs: period, semicolon, comma plus coordinating conjunction (for, and, nor, but, or, yet, so), or subordination. Watch especially for conjunctive adverbs like however, therefore, and moreover, which need a semicolon or period before them, not a comma.
Confusing adjectives with adverbs, writing 'She sings good', 'He did real well', or 'Drive careful' because the shorter form sounds natural in speech.
Colloquial speech routinely drops the -ly ending, and linking verbs complicate the rule: after verbs like feel, taste, smell, look, seem, and become, an adjective is actually correct ('The soup tastes good'), which leads candidates to overcorrect in the other direction and add -ly where it does not belong.
What to do instead
Ask what the word modifies: if it describes a noun or follows a linking verb, use the adjective; if it describes how an action is performed, use the adverb. Memorize the linking-verb list so 'tastes good' and 'feels bad' are recognized as correct. Practice contrasting pairs aloud ('quick' versus 'quickly', 'real' versus 'really', 'good' versus 'well') and note that 'well' can also mean healthy, as in 'She feels well'.
Misplacing or omitting commas around nonessential elements, so restrictive and nonrestrictive clauses are punctuated identically, as in 'My brother, who lives in Ohio, is a nurse' versus 'My brother who lives in Ohio is a nurse' being treated as interchangeable.
The distinction is semantic rather than auditory: the same words can be essential or extra depending on whether the clause identifies the noun or merely comments on it. Candidates punctuate by where they would pause, and pauses do not reliably track the restrictive/nonrestrictive line.
What to do instead
Test by deletion: if removing the clause leaves the sentence meaning intact and still identifies the same person or thing, the clause is nonessential and takes commas; if removal changes which entity is meant, it is essential and takes none. Apply the same deletion test to appositives and to phrases beginning with 'that' (always restrictive, no comma) versus 'which' (usually nonrestrictive, comma). Also check introductory elements and items in a series separately.
Selecting the wrong verb tense or form in a sentence that contains a time marker or a second verb, for example 'By the time we arrived, the movie had already started' written as 'has already started', or 'I have saw' instead of 'I have seen'.
Candidates match tense to the moment of speaking rather than to the timeline the sentence establishes, and irregular past participles are memorized incompletely, so 'seen', 'written', 'taken', and 'gone' get replaced by their simple past forms after have, has, or had.
What to do instead
Draw the timeline before choosing: identify which action happened first and mark it with past perfect (had plus participle) when a later past action is also named. Memorize the three principal parts of common irregular verbs (go/went/gone, see/saw/seen, write/wrote/written, take/took/taken, begin/began/begun) and drill the participle after have, has, and had. Treat 'since', 'for', 'by the time', 'already', and 'never' as signals to check whether perfect aspect is required.
Mismatching parallel structure in a list or comparison, producing 'She likes hiking, swimming, and to bike' or 'The new policy is clearer and it saves time' where the joined elements are different grammatical forms.
The candidate checks each item for correctness in isolation rather than checking that all items share the same form, and comparisons are left incomplete ('My score was higher' without saying higher than what), which reads as acceptable because the missing piece is understood in conversation.
What to do instead
Underline every element joined by and, or, but, or a correlative pair (either...or, not only...but also, both...and) and confirm each has the same grammatical shape: all gerunds, all infinitives, all nouns, or all clauses. For comparisons, verify that both sides are present and comparable, and watch for illogical comparisons such as 'The cost of housing in Boston is higher than New York', which compares a cost to a city.
Leaving modifiers dangling or misplaced, as in 'Walking to the store, the rain started' or 'Covered in frosting, she handed out the cupcakes', where the opening phrase describes the wrong noun.
The writer knows what they mean and supplies the missing subject mentally, so the sentence feels coherent. Introductory participial phrases are also common in formal writing, and candidates imitate the structure without checking what the phrase attaches to.
What to do instead
Read the introductory phrase and then ask who or what performs that action; that noun must be the first noun after the comma. If it is not, either rename the subject ('Walking to the store, I felt the rain start') or convert the phrase into a clause ('As I walked to the store, the rain started'). Apply the same check to appositives and to single-word modifiers like 'only', which changes meaning with position.
Confusing commonly swapped word pairs and homophones, choosing 'affect' for 'effect', 'their' for 'there', 'then' for 'than', 'lie' for 'lay', or 'fewer' for 'less' based on sound rather than function.
These pairs are near-identical in pronunciation and are frequently mistyped in casual writing, so the wrong form looks familiar. The distinctions depend on part of speech or countability, which the candidate is not checking under time pressure.
What to do instead
Memorize each pair with a fixed diagnostic: affect is usually the verb and effect the noun; their shows possession, there shows place or existence, they're contracts 'they are'; than compares and then marks time; fewer counts individual items and less measures quantity; lay takes an object and lie does not. Write one sentence for each pair that makes the distinction visible and review that list before the exam rather than relying on how the word sounds.
Answering by ear under time pressure without reading all four options, so the candidate picks the first choice that sounds acceptable and moves on before noticing that a later option is grammatically cleaner.
The grammar section is short and timed, which encourages speed, and spoken habits make familiar but incorrect constructions sound right. The first plausible option anchors the judgment, and remaining options get skimmed rather than tested.
What to do instead
Read the full sentence and all four options before deciding, then eliminate options for a named reason (subject-verb agreement, pronoun case, tense, parallelism) instead of choosing by feel. When two options both sound fine, look for the specific difference between them and apply the relevant rule. Budget roughly thirty to forty seconds per item, and mark uncertain items to revisit rather than stalling on one question.