you only can use 수고했어 to your friends or people who are younger than you. Even though they are younger than you, if you are not familiar with them, you must not say 수고했어. you have to say 수고했어요 or 수고하셨습니다. They are honorifics.
The Language Level symbol shows a user's proficiency in the languages they're interested in. Setting your Language Level helps other users provide you with answers that aren't too complex or too simple.
Has difficulty understanding even short answers in this language.
Can ask simple questions and can understand simple answers.
Can ask all types of general questions and can understand longer answers.
Can understand long, complex answers.
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