Lesson · G.3.4

Commonly confused word pairs

The HESI A2 Grammar section tests confused word pairs like affect versus effect and lie versus lay head on. Learn the one rule that settles each pair, with clear clinical examples.

ObjectiveG.3.4Read5 minExam weightCommon Errors and Usage ≈ 36% of Grammar

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What you will be able to do

Choose correctly between the word pairs the HESI A2 tests most often, including affect and effect, lie and lay, and who and whom.
Apply the countable versus bulk rule to amount, number, fewer, and less.
Tell an essential clause from a nonessential one to choose which and that correctly.

What the lesson concludes

Affect is nearly always a verb meaning to influence. Effect is nearly always a noun meaning a result.
Lie is intransitive and takes no object. Lay is transitive and always takes one.
Fewer counts, less measures. Amount is for bulk, number is for countable units.
Who does the action, whom receives it. Substitute he or him to check.
That introduces a clause the sentence needs. Which introduces one you could delete.