COMPARISON

                                       How shall we travel?  By car or by train?

                                             Let´s go by car. It is cheaper.

                                      Don´t go by train. It is more expensive.

Cheaper and more expensive are comparative forms.

After comparatives you can use than

It is cheaper to go by car than train

Going by train is more expensive than going by car.

The comparative form is er- or more...

We use -er for short words (one syllable)

cheap - cheaper                             fast - faster
large - larger                                  thin - thinner

We also use -er for two-syllable words that end in -y (-y - ier)

Lucky - luckier                              early - earlier
easy - easier                                  pretty - prettier

You are older than me.
I would like to have a bigger car.

We use more... for longer words (two syllables or more)
more modern                              more serious
more quietly                                more comfortable

You are more patient than me.

These adjectives and adverbs have irregular comparative forms:

good / well  - better 

I know him well, probably better than anybody else.

bad / badly - worse

He did very badly in the exam, worse than expected.

far - further (or father).

It is long walk from here to the station, further than I thought.