I went a couple of times a couple of years ago, but perfectly is not how I sight-sing.    From Wordnik.com.  [Music on the horizons] Reference

He was surrounded by music from birth and learned to sight-sing (that is, to use sol-fa syllables for practicing melodies).    From Wordnik.com.  [Frank Loesser] Reference

She flattened out the music and attempted to sight-sing the opening bars, but could not catch the melody even though it was very plain.    From Wordnik.com.  [Sepulchre]

For God's sake, even amateur musicians singing in churches or glee clubs are expected to look at a piece of music and know what's on it, and maybe even sight-sing their parts on the spot.    From Wordnik.com.  [Music You (Possibly) Won't Hear Anyplace Else] Reference