题干
—Who taught Zhu Zhiwen to sing? —________! He learned singing by himself.
A：Everybody
B：Somebody
C：Nobody
答案(点此获取答案解析）
C
—Who taught Zhu Zhiwen to sing? —________! He learned singing by himself.
A：Everybody
B：Somebody
C：Nobody
满足约束条件
，若目标函数
的最大值为
,则
的最小值为（ ）