What do you add to the end of most one syllable and some two adjectives form a comparison or superlative?

You add -er for the comparative form and -est for the superlative form.

Here are some examples:

Comparative:

* Short + er = Shorter

* Big + er = Bigger

* Fast + er = Faster

Superlative:

* Short + est = Shortest

* Big + est = Biggest

* Fast + est = Fastest

Important Note:

There are some exceptions to this rule. For example:

* Good becomes better and best

* Bad becomes worse and worst

* Far becomes further and farthest

These words have irregular comparative and superlative forms.