jià qīng jiù shú

ㄐㄧㄚˋ ㄑㄧㄥㄐㄧㄡˋ ㄕㄨˊ

Idiom

1lit. an easy drive on a familiar path (idiom); fig. experience makes progress easy

2a task that is so familiar one can do it with one's hand tied behind one's back