Writing or to write?

Question

"Peter is very good at ( ) stories" . I chose 'to write' to fill ()but correct answer was 'writing'. Can anyone explain why 'to write' was wrong and 'writing' is correct?

Answer 1

Some verbs only take a gerund as an object, such as write, keep, finish, practice, quit and recommend.

Peter is very good at writing stories.

Some verbs only take an infinitive as an object, such as ask, agree, demand and hope.

Peter agreed to write the story for homework.

Other verbs can take either, without a difference in meaning, such as like, love, hate and remember.

Peter likes to write stories.

Peter likes writing stories.

Still others can take either, but have a difference in meaning, such as forget, remember and stop.

Peter stopped writing stories.

Peter stopped to write a story.

Unfortunately, you're just going to have to learn which category a verb falls into through reading, listening and practicing.

Answer 2

At is a preposition. As far as I know, a preposition cannot be followed by to + infinitive. Rather, it must be followed by a gerund (the -ing form). Let's consider similar constructions and see how the choice of verbs is irrelevant:

He sucks at swimming.
He excels at cooking.

And now some other prepositions:

He always coughs after running.
You can't make an omelet without breaking a few eggs.

So we do not have to memorize a long list of verbs to understand this particular rule.

You can find more examples at Grammaring and voanews, among other sites.