“用功的”的英语可以翻译为：diligent，hardworking，operose ...

用功的学生在这门功课上偶尔也不及格.Diligent students occasionally fail this subject.他是个用功的但不是很聪明的孩子。He's a hardworking but not very intelligent boy.我们对那些默默无闻地刻苦用功的人脱帽表示敬意.We take off our hats to those who are quietly working hard....