From English - German Ding/FreeDict dictionary ver. 1.9-fd1:
sing /sˈɪŋ/ (sang /sˈaŋ/ <>, sung /sˈʌŋ/ <>) <v>
singen <v, intr> [mus.]
"he/she sings" - er/sie singt
"I/he/she would sing" - ich/er/sie sänge
"sing in tune" - sauber singen, rein singen, richtig singen
"sing out of tune" - falsch singen
"sing off-pitch" - falsch singen
"sing off-key" - falsch singen
"sing in parts" - mehrstimmig singen
"sing in harmony" - mehrstimmig singen
"sing in a choir" - in einem Chor singen / mitsingen
"Why don't you sing something pretty?" - Sing mal etwas Schönes!
see: singing, sung, I/he/she sang, we/they sang, sing treble