After studying in a medical college for five years, Jane her job as a doctor in the countryside. A.set out B.took over C.took up D.set up 答案:C 解析: set out“出发, 开始” take over“接收, 接管”take up“从事” set up“设立”根据题意,应选C。(本小题满分13分)
设函数
(I)若当时,取得极值,求的值,并讨论的单调性;
(II)若存在极值,求的取值范围,并证明所有极值之和大于.