সহায়িকা

The missing word is can to complete the sentence: "I am looking for someone who can play the piano". Other grammatically correct options include "is able to," but "can" is the most common and direct way to express the ability to play the piano.
Can: This is the most common and direct way to express the ability to play the piano. The sentence is grammatically correct as "I am looking for someone who can play the piano."
Is able to: This is also grammatically correct, though slightly more formal: "I am looking for someone who is able to play the piano."
Can be able to: This is redundant and grammatically incorrect, so it should be avoided.

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