Efficient at or in


Which is the difference in meaning by placing the preposition "at" and "in" after "efficient"?, when should I use one preposition and when the other?

*Their equipment was not as efficient at finding gold as today's machinery.

*The heating system is very efficient in its use of fuel.
  • scrotgrot

    Senior Member
    English - English
    I think it might be the object that matters.

    Efficient in its use of fuel but efficient at using fuel.


    Senior Member
    In many situations, DeivDave, either preposition means the same thing. Here's such an example:

    She's efficient at everything she does.
    She's efficient in everything she does.

    Both sentences mean the same thing. In your examples, I like the prepositions as they are used. Efficient at finding gold (in is possible). Efficient in its use of fuel (Scotgrot's suggestion "efficient at using fuel" sounds good too).

    A good dictionary is probably your best aid in finding the prepositions most commonly used after particular words. Any dictionary that provides these words in context will be especially helpful.
    Last edited:
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