Question

바이올린을 잘 켜려면 많은 연습이 필요해요 The subject particle -이/가  is used when talking about having (있다) or not having (없다) something in one's possession, having many (많다), a lack (부족하다) or a need (필요하다) of something. The -이/가-marked word would act as a subject in structures meaning 'for someone, ...이/가 exists/doesn't exist', 'for someone, ...이/가 is plentiful/ scarce/ necessary'. In such phrases, the first noun is commonly marked by the topic marker (-은/는), by the locative (-에게/한테) or by the combination of two.

Accepted Answer

It takes a lot of practice to play the violin well

Front	바이올린을 잘 켜려면 많은 연습이 필요해요
Back	It takes a lot of practice to play the violin well
Notes	The subject particle -이/가 is used when talking about having (있다) or not having (없다) something in one's possession, having many (많다), a lack (부족하다) or a need (필요하다) of something. The -이/가-marked word would act as a subject in structures meaning 'for someone, ...이/가 exists/doesn't exist', 'for someone, ...이/가 is plentiful/ scarce/ necessary'. In such phrases, the first noun is commonly marked by the topic marker (-은/는), by the locative (-에게/한테) or by the combination of two.

Subject 이/가 바이올린을 잘 켜려면 많은 연습이 필요해요