Masterclass: SC – Idioms & Diction • GMATCourse.mba

Core Philosophy: Idiomatic Standard English

Idiom questions test whether you know the conventional preposition, word form, or phrase that Standard Written English requires in a given context. The "correct" idiom is not always logical — it is simply established by convention.

The GMAT tests two types of idiomatic errors: (1) wrong preposition ("different than" instead of "different from"), and (2) diction errors (choosing the wrong word from a near-pair like "affect/effect," "less/fewer," "amount/number").

Core Insight: Idiom knowledge is built through exposure, not derivation. Learn the high-frequency GMAT idioms as fixed phrases, not rules.

The Two Types of Idiom Questions

Idiom Question Types

Type 1: Prepositional Idioms

different from (not "than" or "to")

consists of (not "in" or "with")

attribute X to Y

result in (not "to")

regard X as Y

Type 2: Word Choice / Diction

fewer (countable) vs less (uncountable)

number (countable) vs amount (uncountable)

affect (verb) vs effect (noun)

between (2) vs among (3+)

like (comparison) vs as (conjunction)

The Idiom-Test Strategy

Recognize the idiom trigger

Certain verbs, adjectives, and nouns are always paired with specific prepositions. When you see them, check the preposition first.

Test the preposition against the fixed form

Ask: what preposition does this verb/adjective always take? Eliminate choices with the wrong preposition.

For diction questions: apply the count/non-count test

Can you count the noun? If yes → fewer, number. If no → less, amount. If comparing with a clause → as, not like.

When in doubt, eliminate the clearly wrong options first

On idiom questions, even partial idiom knowledge can let you eliminate 2–3 choices by spotting obvious errors.

Worked Examples

Example 1 — Prepositional Idiom

✗ The increase in sales is different than we expected.

✓ The increase in sales is different from what we expected.

Rule: "different from" is the standard GMAT idiom. "Different than" is colloquial but not accepted on the GMAT.

Example 2 — Fewer vs Less

✗ The new process uses less steps than the previous one.

✓ The new process uses fewer steps than the previous one.

"Steps" are countable → "fewer." Use "less" only for uncountable nouns (less water, less time, less money).

Example 3 — Like vs As

✗ Like the report indicates, the project is behind schedule.

✓ As the report indicates, the project is behind schedule.

"Like" compares nouns/pronouns. "As" introduces clauses (with a verb). "The report indicates" is a clause → use "as."

10 High-Frequency Idiom Traps

1. "Different than" trap

GMAT requires "different from." "Different than" is colloquial.

2. "Less" with countable nouns

Use "fewer" with countable nouns (items, steps, people), "less" only with uncountable.

3. "Amount of" with countable nouns

Use "number of" with countable nouns.

4. "Like" used as a conjunction

Use "as" or "as if" when introducing a clause containing a verb.

5. "Between" with more than two items

Use "among" for three or more items.

6. "Due to" vs "because of"

On GMAT, "due to" should follow a form of "be"; "because of" introduces a reason for a verb.

7. "Not only X but also Y" dropped "also"

The idiom requires "also" — "not only X but Y" is incomplete.

8. "Regard as" vs "consider as"

GMAT: "consider X [to be] Y" (no "as"). "Regard X as Y" (with "as").

9. "Attribute to" vs "attribute with"

Always "attribute X to Y" — never "attribute X with Y."

10. "Prohibit from" vs "prohibit to"

Always "prohibit someone from doing" — never "prohibit to do."

High-Frequency GMAT Idioms

Idiom	Correct Form	Wrong Form
Differ	differ from	differ with/than
Result	result in	result to
Consist	consist of	consist in
Credit	credit X to Y / credit Y with X	credit X for Y
Native	native to	native of
Prohibit	prohibit from doing	prohibit to do
Regard	regard X as Y	regard X to be Y

10 GMAT-Style Practice Questions

Select your answer, then reveal the step-by-step explanation. Each question reflects real GMAT difficulty and format.

Question 1 of 10 GMAT Verbal

The results of the clinical trial were markedly different [from/than/to/with] those reported in the earlier pilot study. Which preposition is idiomatically correct?

Correct Answer: (B)

(B) is correct. "Different from" is the standard GMAT idiom. "Different than" is accepted in informal English but not on the GMAT. "Different to" and "different with" are always wrong. (E) uses "differing from" — changes the modifier structure unnecessarily.

Question 2 of 10 GMAT Verbal

The updated guidelines [prohibit employees to use / prohibit employees from using / prohibit the use by employees of / prohibit using by employees] personal devices during working hours. Which is idiomatically correct?

Correct Answer: (B)

(B) is correct. The idiom "prohibit [person] from [doing]" is standard. "Prohibit to do" is always wrong. (C) is grammatically acceptable but awkward and less direct. (D) omits the required preposition "from." (E) uses a possessive gerund — technically acceptable but awkward compared to (B).

Question 3 of 10 GMAT Verbal

The company's rapid growth can be largely [attributed to/attributed with/credited to/credited for] its aggressive expansion into emerging markets. Which version is idiomatically correct?

Correct Answer: (A)

(A) is correct. "Attribute X to Y" is the correct idiom: "The growth can be attributed to the expansion." "Attribute X with Y" is wrong. Note: "credited with" is also a valid idiom, but the sentence says "can be attributed," so the correct answer must use "attribute...to." (C) would require restructuring: "Its growth can be credited to/The company can be credited with."

Question 4 of 10 GMAT Verbal

The new streaming service has attracted a larger [number/amount/quantity/volume] of subscribers than analysts predicted for its first quarter.

Correct Answer: (B)

(B) is correct. "Subscribers" are countable → use "number of." "Amount of" is for uncountable nouns (amount of water, amount of money). (C) "quantity of" works for countable items but is less precise and natural here. (D) "volume of subscribers" is informal and not GMAT standard. (E) "count of" is non-standard.

Question 5 of 10 GMAT Verbal

The agreement was reached [between/among] the five member nations after three days of intensive negotiation. Which is correct?

Correct Answer: (B)

(B) is correct. "Among" is used when referring to three or more entities. "Between" is traditionally for exactly two entities, though modern usage allows it for more when the relationship is one-to-one. On the GMAT, use "among" for groups of three or more when making a general reference. (C) "Amongst" is British English — GMAT uses American English.

Question 6 of 10 GMAT Verbal

The research team considered the new compound [as a viable treatment / a viable treatment / to be a viable treatment / viable as a treatment] for the condition. Which is idiomatically correct on the GMAT?

Correct Answer: (B)

(B) is correct. The GMAT idiom "consider X Y" (without "as" or "to be") is preferred for direct object constructions: "considered the compound a viable treatment." Both (B) and (C) are acceptable, but (B) is more concise. (A) uses "considered X as Y" — incorrect idiom on GMAT. (D) would require "regarded X as Y" — also correct but changes the verb.

Question 7 of 10 GMAT Verbal

The new regulations, [like/as/similar to/in the manner that] those implemented in 2018, are expected to reduce industrial emissions by 15%. Which is correct when comparing the new regulations to the earlier ones?

Correct Answer: (A)

(A) is correct. "Like" introduces a comparison between two nouns/noun phrases. "Those implemented in 2018" is a noun phrase (no finite verb), so "like" is appropriate. (B) "as" would require a clause with a verb: "as those implemented in 2018 were." (E) inverts the structure awkwardly. (C) is wordy and redundant.

Question 8 of 10 GMAT Verbal

The board has decided to [forbid/prevent/prohibit/ban] the CFO from disclosing the merger details before the official announcement. All of the following could be correct EXCEPT:

Correct Answer: (E)

(E) is correct (the EXCEPT answer). "Restrict to" means to limit someone TO only that action, which changes the meaning. "Restrict the CFO to disclosing" would mean the CFO is limited to disclosing information (the opposite intent). All of (A)-(D) correctly use "from" with their respective verbs to convey prohibition.

Question 9 of 10 GMAT Verbal

The results of the study indicate that the drug has [less/fewer] side effects than the currently approved treatment. Which is correct?

Correct Answer: (B)

(B) is correct. "Side effects" are countable → use "fewer," not "less." "Fewer side effects" is the standard GMAT form. (A) uses "less" with a countable noun — classic error. (C) is wordy. (E) changes meaning slightly and is wordier.

Question 10 of 10 GMAT Verbal

The new policy is intended to [effect/affect] a change in how the company handles customer complaints. Which word is correct?

Correct Answer: (B)

(B) is correct. "Effect" as a verb means "to bring about" or "to cause." "Effect a change" = bring about a change. "Affect" as a verb means "to influence or impact" — it doesn't pair with "a change" in this construction. (A) "affect a change" is non-idiomatic. (D) is correct but changes the sentence structure unnecessarily. (E) "affect" is not a noun in Standard English (in this context).

Key Takeaways

1. "Different from" not "different than"

The GMAT recognizes only "different from" as standard.

2. Fewer/less, number/amount

Countable → fewer/number. Uncountable → less/amount.

3. "Like" vs "as"

"Like" compares nouns. "As" introduces clauses with verbs.

4. Know your fixed prepositions

Attribute to, consist of, result in, prohibit from — learn them as units.