Teaching Ling Ling reading and writing would make her irritable, and her illness would attack easily. Therefore, Wu Chengyue didn't dare to do that.
Before, he didn't know what the little girl was interested in. If Lin Qiao didn't show up, Wu Chengyue might only be able to provide her with enough food and clothes, and keep her safe and healthy.
Not long ago, Wu Yueling was with Lin Qiao in Upper City Base. Back then, the latter taught her how to draw. After that, she slowly grew fond of drawing. Now, she often stayed in Wu Chengyue's office alone, drawing all sorts of things on a notebook.
However, Lin Qiao wasn't the one who taught her to write. In fact, it was Lin Xiaolu.