[dān dú]

travel alone; single-handed journey
單獨旅行

take independent action
采取單獨行動

He has a room to himself.
他單獨住一間屋子。

I want to have a talk with him alone.
我要和他單獨談一談。

Nobody can do this job alone [by himself].
單獨一個人干不了這個活。