not____until____哪句是主句?

应该是until前面部分是主句,如（He did not come）until 2 o'clock.括号部分是主句，until 后面是时间状语

以下面一个例句作分析：
He didn't come back until 9:00 last night.
这句主句是He didn't come back
until 9:00 last night是时间状语从句。

not后是主句
不妨把until后看成时间状语从句