When we talk about two things, we can "compare" them. We can see if they are the same or different. Perhaps they are the same in some ways and different in other ways. We can use comparative adjectives to describe the differences.

We use comparative adjectives when talking about two  things (not three or more things).

In the example below, "bigger" is the comparative form of the adjective "big":

A1    A2 
A1 is bigger  than A2.

Formation of Comparative Adjectives

There are two ways to make or to "form" a comparative adjective:

  • short  adjectives: add "-er"
  • long  adjectives: use "more"
Short adjectives: add -erexamples
1-syllable adjectivesold, fast
2-syllable adjectives ending in -yhappy, easy
RULE:  add "-er"old → older
Variation: if the adjective ends in -e, just add -rlate → later
Variation: if the adjective ends in consonant, vowel, consonant, double the last consonantbig → bigger
Variation: if the adjective ends in -y, change the y to ihappy → happier
Long adjectives: use moreexamples
2-syllable adjectives not ending in -ymodern, pleasant
all adjectives of 3 or more syllablesexpensive, intellectual
RULE:  use "more"modern → more modern
expensive → more expensive
With some 2-syllable adjectives, we can use "-er" OR "more":

quiet → quieter/more quiet
clever → cleverer/more clever
narrow → narrower/more narrow
simple → simpler/more simple
Exception:  The following adjectives have irregular forms:

good → better
well (healthy) → better
bad → worse
far → farther/further

Use of Comparative Adjectives

We use comparative adjectives when talking about 2 things (not 3 or 10 or 1,000,000 things, only 2 things).

Often, the comparative adjective is followed by "than".

Look at these examples:

  • John is 1m80. He is tall. But Chris is 1m85. He is taller than John.
  • America is big. But Russia is bigger.
  • I want to have a more powerful computer.
  • Is French more difficult than English?

If we talk about the two planets Earth and Mars, we can compare them as shown in the table below:

 EarthMars 
Diameter (km)12,7606,790Mars is smaller  than Earth.
Distance from Sun (million km)150228Mars is more distant from the Sun.
Length of day (hours)2425A day on Mars is slightly longer  than a day on Earth.
Moons12Mars has more  moons than Earth.
Surface temperature (degrees Celsius)22-23Mars is colder  than Earth.
Although we use comparative adjectives when talking about two  things (not three or more things), in fact one or both of the things may be a group of things.
  • Mt Everest is higher than all other mountains.
Here, we are talking about hundreds of mountains, but we are still comparing one thing (Mt Everest) to one other thing (all other mountains).

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