老师临时有事，所以另一位老师来代课了。

The teacher was unavailable, so another teacher ___subbed in for the class.

我订阅了一个在线音乐平台，这样就能随时听歌了。

I ___subscribed to an online music platform so I can listen anytime.

今天老师生病了，所以王先生来代课。

The teacher was sick today, so Mr. Wang ___subbed for her in class.