知ㄓzhī易ㄧˋyì行ㄒㄧㄥˊxíng難ㄋㄢˊnán

了解事物的道理很容易，做起來卻很難。語本《書經·說命中》：「非知之艱，行之惟艱。」漢·孔安國·傳：「言知之易，行之難。」

英easy to grasp but difficult to put into practice (idiom), easier said than done