Even though she became fatally ill from working with radium, Marie Curie was never disappointed.
Explanation: The word "disappointed" suggests a sense of unfulfilled expectation or sadness about outcomes. In this context, it emphasizes that despite the severe health consequences of her work with radium, Marie Curie never regretted or became disillusioned with her scientific pursuits. She remained dedicated to her research and mission to uncover the mysteries of the physical world, regardless of the personal cost.