American Diploma · ACT · English: Sentence Structure

Faulty Comparisons

Compare like with like — that of / those of, possessive fixes, like/unlike openers, "than any other" and comparison forms, with four worked items and two ACT-style practice essays.

American Diploma › ACT English and Reading — Complete Course

What this question type tests

Faulty-comparison questions belong to the Conventions of Standard English reporting category of the ACT English test (38–43% of the English score, together with punctuation, usage and the other sentence-structure skills). The English test has 50 questions (40 scored) in 35 minutes, over five essays: three of about 340 words with 10 questions each and two of about 185 words with 5 questions each.

As with every ACT English item, a part of the essay is underlined and numbered, and you choose the best of four versions (the first is usually NO CHANGE). You know a comparison item is in front of you when the choices add or remove words such as that of, those of, 's, other, than/then, more/most, -er/-est, or when they reorder the words after *like* or *unlike*.

The core rule: a comparison must compare two things of the same kind. A population with a population, a city with a city, one writer's style with another writer's style. Everyday speech is often careless ("My phone is better than yours" is fine, but "My phone's camera is better than you" is not), and the ACT turns that carelessness into wrong answers. The sentence often *sounds* fine — that is exactly why these questions are hard.

الفكرة الأساسية

المقارنة لازم تكون بين حاجتين من نفس النوع: عدد سكان مع عدد سكان، مدينة مع مدينة، مقال مع مقال. اسأل نفسك: إيه الحاجتين اللي بنقارنهم بالظبط؟ لو واحدة شيء والتانية شخص أو مكان، المقارنة غلط.

Rule 1: Name the two things being compared

Before you look at the choices, say the two things in your own words. Ask: "What is bigger / older / better than what?" The first thing is usually the subject; the second comes after *than*, *as*, *like*, *unlike*, *similar to*, *different from* or *compared with*.

Mismatch	✗ Faulty comparison	✓ Logical comparison
Quality vs place	The climate of Aswan is drier than Alexandria.	The climate of Aswan is drier than that of Alexandria.
Possession vs owner	Salma's handwriting is neater than her brother.	Salma's handwriting is neater than her brother's.
Part vs whole	The roof of the new school is higher than the old school.	The roof of the new school is higher than that of the old school.
Work vs person	The novels of Naguib Mahfouz are longer than most writers.	The novels of Naguib Mahfouz are longer than those of most writers.
Action vs person	Cycling to work is faster than my neighbour.	Cycling to work is faster than my neighbour's daily drive.
Group vs individual	Like a doctor, a nurse's training takes years.	Like a doctor's training, a nurse's training takes years.

Rule 2: The three standard fixes — that of, those of, 's

When the second thing in a comparison is missing, the ACT repairs it in one of three ways. All three are correct; choose the one the choices offer, and check that it fits grammatically.

that of — replaces a singular noun: "The population of Egypt is larger than that of Canada." (that = the population)
those of — replaces a plural noun: "The pyramids of Giza are older than those of Mexico." (those = the pyramids)
possessive 's — the noun is understood after it: "Egypt's population is larger than Canada's." (Canada's = Canada's population)
repeat the noun — always safe, sometimes wordy: "Egypt's population is larger than Canada's population."

Match the number. *That* must point back to a singular noun and *those* to a plural noun. This is where many careful students lose the point:

✗ The streets of the old city are narrower than that of the new suburbs. (streets = plural)
✓ The streets of the old city are narrower than those of the new suburbs.
✗ The temperature in July is higher than those in January. (temperature = singular)
✓ The temperature in July is higher than that in January.

Prepositions can also fix a comparison. When the first thing is "X *in* a place" or "X *at* a time", repeating the preposition is enough: "Rainfall in Alexandria is higher than in Aswan." "Prices this year are lower than in 2024." Without the preposition, the comparison breaks: ✗ "Rainfall in Alexandria is higher than Aswan."

Possessive pronouns work the same way: *mine, yours, his, hers, ours, theirs*. ✗ "Her score was higher than me." (score vs person) → ✓ "Her score was higher than mine." Note that "She scored higher than I (did)" is also correct — there the two people are compared, because the verb *scored* is the action.

Rule 3: Like, unlike, similar to — the noun after the comma

A sentence that opens with *Like …*, *Unlike …*, *Similar to …* or *As with …* compares the noun in that phrase with the subject that comes right after the comma. The two must be the same kind of thing. This works exactly like a dangling modifier, and it is one of the ACT's favourite traps.

✗ Unlike most desert plants, the leaves of the acacia stay green in summer. (plants vs leaves)
✓ Unlike most desert plants, the acacia stays green in summer.
✓ Unlike the leaves of most desert plants, the leaves of the acacia stay green in summer.
✗ Like his father, Ahmed's career began in a small workshop. (father vs career)
✓ Like his father, Ahmed began his career in a small workshop.
✓ Like his father's career, Ahmed's career began in a small workshop.

The possessive trap: "Like many coastal towns, Rashid's economy depends on fishing." The subject is not Rashid; it is *economy*. A town is being compared with an economy. Fix: "Like many coastal towns, Rashid depends on fishing."

that of و those of

لو الحاجة اللي بتقارنها مفرد استخدم that of، ولو جمع استخدم those of. أو استخدم 's: Egypt's population is larger than Canada's. وفي جمل Like / Unlike: الاسم اللي بعد الفاصلة لازم يكون من نفس نوع الاسم اللي بعد Like.

Rule 4: "Than any other" — do not compare something with itself

When you compare one member of a group with the rest of the group, add other (or else with *anyone, anything, anybody*). Without it, the sentence compares the thing with itself, which is illogical.

✗ Mount Catherine is higher than any mountain in Egypt. (it is a mountain in Egypt — higher than itself?)
✓ Mount Catherine is higher than any other mountain in Egypt.
✗ Mona finished the race faster than anyone on her team.
✓ Mona finished the race faster than anyone else on her team.
✓ The Nile is longer than any river in Europe. (no *other* needed — the Nile is not in Europe)

You can combine Rule 4 with Rule 2: "His descriptions are more detailed than those of any other keeper." Descriptions vs descriptions (those of), and the keeper is not compared with himself (other).

Rule 5: Correct comparison forms

Some items test the form of the comparing word rather than the logic. These are quick points if you know them.

Rule	✗	✓
Two things → -er / more; three or more → -est / most	Of the two plans, the second is the best.	Of the two plans, the second is the better.
Never double: more + -er, most + -est	This road is more safer at night.	This road is safer at night.
Irregular forms	Her second novel is more good than the first.	Her second novel is better than the first.
than (comparison) vs then (time)	The bus is cheaper then the train.	The bus is cheaper than the train.
as … as (never as … than)	The library is as quiet than a mosque at dawn.	The library is as quiet as a mosque at dawn.
different from (ACT standard)	City life is very different than village life.	City life is very different from village life.
fewer (countable) vs less (amount)	Less students attended this year.	Fewer students attended this year.

Rule 6: Illogical, unclear and incomplete comparisons

Ambiguous comparisons. "Nour trusts her coach more than her teammates." Does Nour trust the coach more than she trusts her teammates, or more than her teammates trust the coach? Add the missing verb or pronoun: "…more than her teammates do" or "…more than she trusts her teammates."

Doubled comparison words. Use one comparing structure, not two: ✗ "Compared with last year, sales were higher than before." → ✓ "Sales were higher than last year's." or ✓ "Compared with last year, sales rose."

Comparison with a missing second half. "The new bridge is wider." Wider than what? On the ACT this is acceptable only if the previous sentence already names the other thing ("The old bridge had two lanes. The new bridge is wider."). Read the sentence before the underline.

Comparing the wrong time. "This year's harvest was larger than last year." A harvest is compared with a year. → ✓ "…than last year's." / ✓ "…than the harvest of last year."

A 4-step method for comparison items

Find the comparison signal: than, as … as, like, unlike, similar to, different from, compared with, more/most, -er/-est.
Name thing 1 and thing 2 in plain words ("the price … bananas").
Ask: same kind? If not, look for the choice with *that of / those of / 's / in*, or the choice that changes the subject after *Like/Unlike*. Check singular vs plural for that/those.
Check the extras: *other/else* for a member of its own group; than not then; -er for two, -est for three or more; no *more + -er*.

Worked examples

Worked example 1 — a missing "in" / "that of"

Passage: Because the city lies on the Mediterranean, the winter rainfall in Alexandria is much higher __than Aswan__, where rain may not fall for years.

Choose the best version of the underlined portion.

A) NO CHANGE
B) than in Aswan
C) than those of Aswan
D) then in Aswan

Answer: B

A) ✗ Wrong: Compares rainfall with a city.
B) ✓ Correct: *Rainfall in Alexandria … than in Aswan* — rainfall compared with rainfall; the repeated *in* brings back the missing noun.
C) ✗ Wrong: *Those* is plural, but *rainfall* is singular.
D) ✗ Wrong: *Then* is a time word, not a comparison word.

Worked example 2 — than any other

Passage: At 2,629 metres, Mount Catherine in South Sinai is higher __than any mountain__ in Egypt.

Choose the best version of the underlined portion.

A) NO CHANGE
B) then any other mountain
C) than any other mountain
D) than all the mountains

Answer: C

A) ✗ Wrong: Mount Catherine is itself a mountain in Egypt, so without *other* it is compared with itself.
B) ✗ Wrong: Adds *other* but uses *then* (time) instead of *than*.
C) ✓ Correct: *Than any other mountain* compares it with the rest of the group, not with itself.
D) ✗ Wrong: *All the mountains* in Egypt still includes Mount Catherine — the same illogical comparison.

Worked example 3 — unlike + the subject after the comma

Passage: __Unlike most smartphones, the battery of this model__ can be replaced at home with a simple screwdriver.

Choose the best version of the underlined portion.

A) NO CHANGE
B) Unlike the batteries of most smartphones, the battery of this model
C) Unlike that of most smartphones, this model
D) Unlike most smartphones, this model's battery

Answer: B

A) ✗ Wrong: Compares smartphones with a battery.
B) ✓ Correct: Batteries compared with a battery — the same kind of thing on both sides of the comma.
C) ✗ Wrong: *That of* has no clear noun to point back to (it comes before the noun it replaces), and the subject is now *this model* — a model compared with a battery.
D) ✗ Wrong: Possessive trap: the subject is *battery*, not *model*, so phones are still compared with a battery.

Worked example 4 — possessive pronoun

Passage: Omar's sketches of the old Cairo streets are far more detailed __than me__, so the teacher asked him to draw the class poster.

Choose the best version of the underlined portion.

A) NO CHANGE
B) than mine
C) than I
D) than my

Answer: B

A) ✗ Wrong: Sketches compared with a person.
B) ✓ Correct: *Mine* = my sketches. Sketches are compared with sketches.
C) ✗ Wrong: *Than I* compares Omar's sketches with a person; it would only work for "Omar draws better than I (do)."
D) ✗ Wrong: *My* must be followed by a noun (my sketches); alone it is ungrammatical.

Classic traps

The sounds-fine comparison: "The population of Alexandria is smaller than Cairo." People say it every day — it is still population vs city.
The wrong-number fix: *that of* for a plural noun or *those of* for a singular one.
The possessive subject after Like/Unlike: "Like many birds, the falcon's eyesight…" — the subject is *eyesight*.
The missing *other*: "better than any student in the class" when the person is in the class.
than/then swap: a choice with the perfect logic but *then* instead of *than*.
The half-fix: a choice that repairs the comparison but adds a tense or agreement error.
Double comparatives: more faster, most best, more better.

Fast strategy for test day

Whenever you see *than*, *as … as*, *like* or *unlike*, stop and name the two things being compared.
Choices that add *that of*, *those of* or *'s* are a strong signal that the test-maker is checking comparison logic.
Check number: singular → *that*, plural → *those*.
After *Like/Unlike …,* the very next noun is the subject being compared — ignore possessive names in front of it.
In a comparison within a group, look for *other* or *else*.
If the original already compares like with like, choose NO CHANGE.

Practice

Two short ACT-style essays with five questions each. Every question refers to the numbered underlined portion. All ten items test comparisons; some wrong choices also contain errors from earlier lessons.

Remember

Compare like with like: name the two things and make sure they are the same kind.
Fix a broken comparison with *that of* (singular), *those of* (plural), *'s*, or a repeated preposition (*than in*).
After *Like / Unlike …,* the noun right after the comma is what is being compared — watch for possessives.
A member of its own group needs *other* / *else*: "than any other mountain in Egypt".
Two things → -er/more; three or more → -est/most; never *more + -er*; *than* not *then*; *as … as*.

All pages in this course

ACT English

ACT Reading