The 5-year average results are illustrated in Fig. . The data indicates that ChatGPT's ability to provide more than 50% accurate answers is for questions 1-21. However, for questions 20-40, the accuracy of ChatGPT's answers decreases significantly to 0. On the other hand, BingChat, Min, and Max have an ability to answer correctly more than 50% for questions 1-24, 1-16, and 1-27 respectively. However, from question 24 onwards, the correct answer rate for Min is approximately 0%. Upon analyzing the accuracy of answers provided by ChatGPT and BingChat, it can be concluded that both models are only capable of answering questions at the knowledge and comprehension levels, and struggle to solve questions at the application and high application levels. 2) Performance evaluation Table presents the performance of LLMs for each year and their averages. ChatGPT achieved the highest score of 62.5 in 2021 and the lowest of 40 in 2019, while BingChat obtained the highest score of 57.5 in 2020 and the lowest of 47.5 in 2022. The Min and Max values showed their best and worst performances in 2022 and 2021, respectively. ChatGPT outperformed BingChat in 2021 only. The bar chart indicates stable performance but varying relative performance across years. Further evaluation is required to determine the optimal method for specific tasks. Fig. depicts the consistency of answers given by ChatGPT and BingChat on the VNHSGE dataset. The findings indicate that BingChat exhibits higher stability compared to ChatGPT. This observation is expected, given that BingChat employs a search engine mechanism, whereas ChatGPT has a more imaginative approach.