6. Please describe "What are free radicals?" "What is oxidative stress?" (6 points) 請描述「什麼是自由基？」「什麼是氧化壓力？」（6 分）

1. CAR-T cell therapy is a novel immunotherapy that has become an effective treatment for hematological malignancies. Describe the principle of CAR-T cell therapy (7 points), and discuss its advantages and challenges in clinical application (6 points). CAR-T 細胞療法是一種新型免疫治療方法，已成為治療血液腫瘤的有效方法。請敘述 CAR-T 細胞療法的原理（7 分），並討論其在臨床應用上的優勢和挑戰（6 分）。