Examples
tiān天bù zhī bù jué不知不觉dì地àn暗le了xià lai下来。
天不知不觉地暗了下来。
It became dark before I knew it.
我们照例寒暄了一阵，闲扯扯队里的新闻以后，他在不知不觉中就把谈话引入了正题。
We exchanged pleasantries, and chatted cordially about news in the team, and he moved the conversation naturally on to the main topic.