GbEng
他演唱由钢琴伴奏. He sang to a piano accompaniment.
那位演唱者的姐姐用钢琴给她伴奏. The singer was accompanied at/on the piano by her sister.
这位歌唱家由她妹妹担任钢琴伴奏。 The singer was accompanied by her sister at the piano.
弹钢琴的人把乐谱忘了, 只好即兴伴奏. The pianist forgot his music and had to improvise (the accompaniment).