I think it is a great question. When I was an elementary/ high school student, my Chinese teacher used to teach us this way. N+ 的。 EX: 我的，媽媽的，我們家的，學校的老師 V+ 得。EX: 跑得快，跳得高，說得好。 ADV use 地。EX:快速地，緩慢地

V+得+ADJ；地+V；的+Noun。e.g.：他学习变得努力了；他跑得快；他飞快地跑；他跑的（速度）快。

always verb+得+adj ， the sentence of "我学习得努力”, sounds not natural, should be like “我学习得很努力”, add 很、非常、十分 etc after the adj, would make the sentence sounds more natural. 我学习努力 is wrong, 学习is a verb, can't be followed by adj. 我努力学习and 我努力地学习 are correct ，努力and 努力地 are adv , because 努力 can be adv or adj, if not , the sentence of 我努力学习could be wrong. For example , can't say我高兴学习, because 高兴is just an adj. the correct version is 我高兴地学习.

这是中文一个特别难得点

看是什么情况