My mother used to _____ up very early

get

My mother used to get up very early.
妈妈过去常常起得很早。
used to do：过去常常，，，

get

get up early 我妈妈过去常常早起。

wake

也可用。语法上没错。意思上差点。 “我妈妈过去老早就醒了”。这就不太好理解了。

get
used to 后面加动词原形

My mother used to get up very early

My mother used to (get) up very early