successful in vs. successful at
 

When do we use in and when do we use at exactly?

I heard an opinion that "in" is used for a specific achievement, and "at" as a generalization, for showing the areas in which someone thrives. Is it any good?

Thanks for your reply!



PS. If I've made any mistakes here, please be so kind as to point them out. Thanks a bunch

Re: successful in vs. successful at
 

It's not just successful, but the whole word family - succeed and success too.

We didn't succeed in repairing the car.
I didn't have much success in persuading Jane to come with us.
He was successful in obtaining a conviction.

Here, the person is talking about specific actions, expressed through a gerund, and in is essential. You couldn't use at

But if you're talking about an activity in general, then at becomes more likely than in:

I was never very successful at making cakes.
He's successful at everything he does.
I never succeed at chess.


But more likely - not obligatory. There are lots of examples of in with general activities too :

He's never been successful at/in forming lasting relationships.
She is more likely to succeed at/in at/in scientific subjects than at/in the humanities.

One thing to keep in mind - just because in/at follow succeeed, success or successful, it doesn't necessarily mean the preposition is dependent on that word. For example , in :

He didn't have much success in Rome.
in Rome is just a preposition of place, telling you where he was at the time. That may seem obvious, but other expressions are more sneaky - eg He's very successful at interviews . Does it mean He's successful when he goes to interviews (preposition of place) or He's successful at being interviewed (preposition dependent on successful).

Re: successful in vs. successful at
 

Thanks, susan, it's a little clearer now.