31. ~うちに

~うちに
Meanwhile; while... (before change)
Structure
N/A conjugate into attributive (noun-modifying) form + うちに, Vない・Vている + うちに
Explanation
Expresses doing something before a state changes; meaning 'take advantage while still...'.
Examples
I want to get down the mountain before it gets dark.
My grandfather says he wants to travel to many places while he's still healthy.
Tomorrow is Mother's Day. While my mother is asleep, I'll make breakfast to surprise her.
I want to decide my future goals while I'm still a teenager.
You should write down important things before you forget them.
~うちに
While... (in the process)
Structure
Vない・Vている + うちに
Explanation
Expresses an event that occurs unintentionally while doing A; often an unwanted or uncontrollable result.
Examples
I fell asleep while watching TV and couldn't study for the exam.
By the time I bought the ticket, the train had already left.
I hadn't seen the child for a while, and he had grown a lot.
Note
1) Easily confuse two uses of ~うちに: 'while/while still unchanged' and 'while... then an unexpected event occurs'.2) Check verb form: Vない/Vている+うちに = 'while...' or 'before a state change'.3) The following clause determines the meaning: 'do X before it's too late/before change' = take advantage; 'while... then...' with unintended result = the second meaning.