Learning disability refers to the impairment of normal ways and means for children to acquire learning skills from the early stages of development. This damage is not the result of a simple lack of learning opportunities, it is not the result of retarded intellectual development, or the acquired brain trauma or disease As a result, this obstacle stems from abnormalities in cognitive processing, manifested as special obstacles in reading, spelling, calculation, etc. According to the above definition, which of the following is learning disabilities? ['Nine-year-old Xiaoqiang has just returned from abroad and cannot recognize simplified characters. He faces many difficulties when reading learning materials.', 'Xiaohua used to be an excellent student. After moving abroad with her parents, her academic performance declined sharply due to difficulties in attending classes.', "Xiao Ming's grades are not good. He took a professional intelligence test in the third grade and found that his intelligence is only equivalent to that of a six-year-old child.", 'Xiao Hong is smart and cute, but after school, she often skips and jumps. Although the teacher repeatedly corrects it, she still has difficulty correcting it.']