Indicates the time or situation when something happens.
When to use
future action timing, habitual situations, advice or caution, conditional situations
The nuance
Attach -(으)ㄹ 때는 to the verb or adjective stem. Use '-을 때는' if the stem ends with a consonant, '-ㄹ 때는' if it ends with a vowel. It mainly expresses the time of a future action or habitual situation.
