Use -아다가/-어다가 to take something somewhere and do something with it there, and -다가 to switch from one action or state to another.
By the end, you can use -아다가/-어다가 when you get something, take it to another place, and use it there. You can also use -다가, -았/었다가 and -다가도 to say that one action stopped or changed into another.
下载功能面向已登录的学习者 —— 注册只需一分钟,而且免费。