Sorry that I didn't explain well... What I meant is for common verb phrases, for example "work in" "come up", Link Parser can combine them with K link, so the RelEx will generate work_in as a verb. Thus the RelEx will have: 
```
He works in science.
   _obj(work_in, science)
    _subj(work_in, he)
```
Then the SVO rule will be applied as usual. R2L will just consider "work_in" as a PredicateNode in this case. 

```
EvaluationLink
       PredicateNode "work_in"
       ListLink
             ConceptNode He
             ConceptNode Science
```

For the general prepositions, we will consider them as PredicateNodes in general. For example:

```
I work in Hong Kong

_subj(work, I)
in(work, Hong_Kong)

EvaluationLink
       PredicateNode "In"
       ListLink
             EvaluationLink 
                   PredicateNode Work
                   ConceptNode I
             ConceptNode Hong_Kong
```
Prepositions can be very ambiguous, so we need different approaches to deal with different prepositions and different cases of course.