wèi / le / shì / yìng / gē / shǒu / de / yīn / yù / lǎo / shī / bǎ / zhè / shǒu / gē / jiàng / diào / le

为了适应歌手的音域，老师把这首歌降调了。

To suit the singer's range, the teacher lowered the key of this song.