求翻译：现在国内对移动学习的定义最具影响力的是由北京师范大学教育技术学院院长黄荣怀教授提出的。他认为“移动学习是指学习者在非固定和非预定设定的位置下发生的学习，或有效利用移动技术所发生的学习。是什么意思？

The definition of the most influential domestic mobile learning is proposed by the Dean of the College of Education, Beijing Normal University Professor Huang Ronghuai. He believes that "mobile learning refers to learners in the non-fixed and non-pre-set position to learn, or effective use of mobile