Quote:



I'm not much interested in grammar gotchas. *yawn*



Yet you can use and probably even construct a sentence like I ran into an old friend in the mall yesterday. You also know that

I ran into an old friend in the mall yesterday.

is correct but

*I ran an old friend into in the mall yesterday.

isn't.

You also know that

I ran up a big bill in the mall yesterday.

and

I ran a big bill up in the mall yesterday.

are both correct and even if you had learned grammar in school you wouldn't have learned why or even that those particular forms existed.