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Playing the piano and singing at the same time is/are not easy.

Which fits better in the above, is or are? Thanks.
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[The act of] playing the piano and singing at the same time is not easy.
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Avangi[The act of] playing the piano and singing at the same time is not easy.
I agree: "It" is not easy to play the piano and sing at the same time.
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Comments  
at the same time gives away the answer.
It is the doing of two things at once that is under consideration.
There is only one doing of two things at once -- one combination of activities.
Therefore, it has to be is.

CJ
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