Plateau phenomenon: It means that students often have a stage in the learning process, that is, when their academic performance reaches a certain level, the rate of continued improvement slows down, and some people even experience stagnation or regression. According to the above definition, which of the following is plateau phenomena? ['As the college entrance examination approaches, Xiao Zheng feels lack of sleep and is less and less motivated to learn.', 'Mock exam for college entrance examination, Xiao Qi is doing well, he feels that he can be admitted to a good university without learning.', 'Three rounds of review in the college entrance examination, Xiao Zhao felt that he did not improve much, thought that the review was useless, and he was unwilling to read again.', 'After the college entrance examination, Xiao Han did well in the exam, and she thought that she had played abnormally.']