I have doubt about the comparitive and superlative form of the adjective “happy”. Some people say both happier and more happy are correct, whereas some say only happier is correct.
With 2-syllable adjectives and adverbs, both forms are often acceptable, Jupiter:
happier / more happy
quieter / more quiet
earlier / more early
It is more a matter of common usage, which you will have to learn (e.g. quieter but not silenter, happier but not pleasanter, etc.). When both are in use, the choice usually depends on style within the context.
Thanks so much for your explanation, MM. But if we have to take the test, which choice is better? I still have a problem althought you said both forms are acceptable because most people (teachers) here think that only “happier” is correct. Can you explain more about this?
There is nothing more to explain. If I were giving the test, both happier and more happy would be correct answers. If your teacher thinks otherwise, I have no way of guessing which way s/he might think is ‘right’.
One general rule is that words ending in ‘-y’ change to ‘-ier’, while words not ending in -y tend to use the ‘more’ form.
I also just found this: Two-syllable adjectives ending in ‘–er’, ‘-le’, or ‘–ow’ take ‘–er’, too.