Because/Since (-(으)니까)
-(으)니까
Expresses reason or cause, usable with imperative and propositive sentences.
Pattern
Verb/Adjective stem + -(으)니까 + Second clause
Explanation
-(으)니까 expresses reason or cause, similar to -아/어서, but with an important distinction: it can be used before imperative (commands) and propositive (suggestions) endings. Use -니까 after stems ending in a vowel and -으니까 after consonants.
For example, 날씨가 좋으니까 산책하자 (Since the weather is nice, let's take a walk) is correct, while using -아/어서 here would be ungrammatical. This makes -(으)니까 essential for giving reasons before commands, requests, and suggestions.
-(으)니까 also has a secondary meaning of discovery: when you do something and discover a result. For example, 문을 열었으니까 고양이가 있었어요 (When I opened the door, there was a cat). Unlike -아/어서, past tense can be used before -(으)니까: 비가 왔으니까 길이 젖었어요 (Because it rained, the road is wet).
Examples
날씨가 추우니까 따뜻하게 입으세요.
Nalssiga chuunikka ttatteuthage ibeuseyo.
Since it's cold, please dress warmly.
시간이 없으니까 빨리 가자.
Sigani eopsunikka ppalli gaja.
Since we don't have time, let's go quickly.
피곤하니까 좀 쉬세요.
Pigonhanikka jom swiseyo.
Since you're tired, please rest a bit.
비가 왔으니까 우산을 가져가세요.
Biga wassunikka usaneul gajyeogaseyo.
Since it rained, please take an umbrella.
Common Mistakes
Wrong
피곤해서 좀 쉬세요.
Correct
피곤하니까 좀 쉬세요.
-아/어서 cannot be used with imperative endings. Use -(으)니까 when the second clause is a command or suggestion.
Wrong
시간이 없니까 빨리 가자.
Correct
시간이 없으니까 빨리 가자.
없다 ends in a consonant (ㅆ), so use -으니까, not -니까.
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