sign off
phrasal verbsign off 
- (British English) to end a letter结束写信 - She signed off with ‘Yours, Janet’.她在信末写上 “你的珍妮特”。 
 
- She signed off with ‘Yours, Janet’.
- to end a broadcast by saying goodbye or playing a piece of music(以说再见或播放音乐的形式)结束广播 
sign something  off 
- to give your formal approval to something, by signing your name签字认可;签名赞同