题干
Tu Youyou was given the Nobel Prize in Physiology or Medicine of 2015 due to her ________ to discovering a new drug to treat parasitic diseases.
A：conservation
B：expectation
C：commitment
D：appreciation
答案(点此获取答案解析）
C
，当
时，
恒成立, 则
的最大值与最小值之和为