5 Degree of Comparison Rules for TOEFL ITP: Comparatives, As...As, Superlatives, The More, and That Of
Degree of comparison in TOEFL ITP Structure: comparatives, as...as, superlatives, the more...the more, and that of/those of, with common traps and a quiz.
“Platinum is more rarer than gold.” It sounds emphatic, but it contains a classic error: a double comparative. Rarer than is enough; more has to go.
Comparison questions (degree of comparison) show up almost every time in TOEFL® ITP Structure & Written Expression. Test writers build sentences that sound natural while one word breaks the formula: an extra more, a than that should be as, a missing the, or an illogical comparison.
Here are the 5 rules you need. (The slides below are in Indonesian, with the English examples.)
The Three Degrees
Before the rules, remember the three degrees:
| Degree | Use | Example |
|---|---|---|
| Positive | Equal / base form | as fast as |
| Comparative | Comparing 2 things | faster than, more efficient than |
| Superlative | The most, among 3 or more | the fastest, the most efficient |
If you still mix up adjectives and adverbs, see Parts of Speech 101.
Rule 1: Comparatives, -ER or MORE … THAN
To compare two things:
- One-syllable adjectives: add -er (hard → harder, fast → faster, rare → rarer).
- Two-syllable adjectives ending in -y: change to -ier (easy → easier, happy → happier).
- Other two-syllable or longer adjectives: use more (more efficient, more expensive).
Then finish with than.
✅ Platinum is rarer than gold. ❌ Platinum is more rarer than gold. ❌ This route is more faster than the old one.
The rule: never combine more with -er. One comparative marker is enough. Also watch for the spelling trap more … then (should be than) and the mismatch more … as.
Rule 2: Equal Comparison, AS + Base Form + AS
For an equal comparison, the word between as … as must be the positive (base) form, with no -er or more.
Formula: as + adjective/adverb (base form) + as
✅ The hybrid motor runs as smoothly as the turbine. ❌ The hybrid motor runs as smoother as the turbine. ❌ This box is as heavy than that one.
Notice also that the middle word follows its function. Runs is a verb, so it’s described by an adverb (smoothly), not an adjective (smooth). If you see as … than or so … than, that’s almost certainly the error.
Rule 3: Superlatives, THE + -EST / MOST
To say the most among three or more things.
Formula: the + adjective-est / most + adjective + in (a place or single group) / of (plural members)
✅ Everest is the highest mountain in the Himalayas. ✅ She is the most diligent of all the students. ❌ Everest is highest mountain in the Himalayas.
The most common trap is the missing the. Then check the scope: in for a place or a group seen as one unit (in the world, in the class), of for plural members (of all, of the three). If you see of all, don’t use in.
Rule 4: Double Comparatives, THE …, THE …
The “the more …, the more …” pattern expresses cause and effect. Both clauses must start with the + comparative.
Formula: The + comparative + S + V, the + comparative + S + V
✅ The older an oak tree grows, the stronger it becomes. ✅ The heavier the baggage (is), the higher the fee. ❌ The older a tree grows, it becomes stronger.
The S + V part can sometimes be dropped when the meaning is clear, as in the second example (the higher the fee). What can’t be dropped is the + comparative at the start of each clause. So if a sentence opens with The more … or The + -er …, look for an option that also starts with the + comparative.
Rule 5: Illogical Comparisons, THAT OF / THOSE OF
This is often the hardest question type in Written Expression. The things compared must be logically equivalent.
❌ The feathers of an owl are softer than a hawk. ✅ The feathers of an owl are softer than those of a hawk.
The wrong sentence compares an owl’s feathers with a whole hawk. Feathers should be compared with feathers. To avoid repeating the noun:
- that of for a singular noun: The climate of Bali is warmer than that of Tokyo.
- those of for a plural noun: The feathers of an owl are softer than those of a hawk.
The signal: a subject shaped like the [noun] of [X]. As soon as you see it, check what comes after than.
The 5 Rules at a Glance
| Rule | Formula | ❌ Trap |
|---|---|---|
| Comparative | adj-er / more adj + than | more rarer than |
| Equal | as + base form + as | as smoother as, as heavy than |
| Superlative | the + -est / most + in/of | highest mountain (no the) |
| Double comparative | The + comp …, the + comp … | …, it becomes stronger |
| Logical comparison | than that of / those of | softer than a hawk |
Quick Quiz
- This exam is _____ than the last one. (more easier / easier)
- The new bridge is as _____ as the old one. (long / longer)
- It is _____ building in the city. (tallest / the tallest)
- The salary of a pilot is higher than _____ a teacher. (that of / those of)
Answers:
- easier (an adjective ending in -y takes -ier, no more).
- long (base form between as … as).
- the tallest (superlatives need the).
- that of (salary is singular).
Practice Comparisons for Real
The comparison rules are simple, but the traps are subtle. To spot an extra more or a misplaced than instantly, you need plenty of practice.
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