袁新东的回答：

not until的三种用法； 陈述句 My mom didn't go to bed until I came back. 倒装句 1。Not until I came back did my mom go to bed. 强调句 2。It was not until I came back that my mom went to bed.

··········的回答：

down falls the water from the top of the mountain. 表位置，方向的副词置于句首时，如果主语是名词，用全部倒装语序 【希望帮助到你，若有疑问，可以追问~~~ 祝你学习进步，更上一层楼！(*^__^*)】

张凯源的回答：

因为not until结构中有否定意，所以当其置于句首时，句子用倒装。 如果不在句首，或者在句首却不修饰状语时，则不用倒装。 希望帮到你！