“天下之事，不难于立法，而难于法之必行。”【英】

the greatest challenge for a country lies not in making laws; but in putting those laws into effect.

译文来源

http://english.qstheory.cn/2015-03/16/c_1114459319.htm

例句

1. “天下之事，不难于立法，而难于法之必行。”——《加快建设社会主义法治国家——习近平在党的十八届四中全会第二次全体会议上的讲话（节选）》

1. It has been said that the greatest challenge for a country lies not in making laws, but in putting those laws into effect.—Quoted from Accelerating the Establishment of Socialist Rule of Law in China —Speech at Session I,II of the Fourth Plenary Session of the Eighteenth CPC Central Committee on October 23, 2014