deep
形容词
deep本身就是形容词
固定搭配：The man often works deep_into the night.
之具体的,时间上的,固定用法deep_into the night.深夜
如你问题所说
The man often works deep_into the night.
之具体的,时间上的,固定用法deep_into the night.深夜deep 后加形容词就是原型
如：deep green