She is well-qualified in typing and very efficient _____ her work.
A. in
B. at
C. with

Note:
1. If I change “her work” with “whatever she does,” do you think A would be the best answer?
2. Do you think B is the best answer because “her work” can be thought of as a location?
3. If I change “her work” with “numbers,” would you say C is the best answer?
4. Do you think in this case, there is some kind of rules or guidelines that tells us whether to use “in”, “at”, or “with”?
Thank you

Question

She is well-qualified in typing and very efficient _____ her work.
A.	in 
B.	at
C.	with

Note: 
1.	If I change “her work” with “whatever she does,” do you think A would be the best answer?
2.	Do you think B is the best answer because “her work” can be thought of as a location?
3.	If I change “her work” with “numbers,” would you say C is the best answer?
4.	Do you think in this case, there is some kind of rules or guidelines that tells us whether to use “in”, “at”, or “with”?
Thank you

Answer

"efficient in" is the phrase. It has nothing to do with location.

Answer

Thanks Miranda but I am a little confused. Does that mean all three prepositions are acceptable, depending on what we want to say?

Answer

It depends on what the preposition is defining.  This should help you understand it better.... http://grammar.ccc.commnet.edu/grammar/prepositions.htm

Answer

hi, 
....very efficient at work ".  (This means her work place).
....very efficient with her work ". (This means she is efficient with what she does) .
:)