下列哪项正确（） A.白癜风多发生于中老年患者 B.有些白癜风沿

搜题请搜索小程序“爱下问搜题”

问题单项选择题

下列哪项正确（）

A.白癜风多发生于中老年患者

B.有些白癜风沿神经节段分布，某些神经介质损伤黑素细胞

C.黄褐斑不发生于男性患者

D.黑变病起病快，自觉症状较微

答案

参考答案：B

解答题

已知函数f（x）=ax⁴lnx+bx⁴-c（x＞0）在x=1处取得极值-3-c，其中a，b，c为常数．

（1）试确定a，b的值；

（2）讨论函数f（x）的单调区间；

（3）若对任意x＞0，不等式f（x）≥-2c²恒成立，求c的取值范围．

补全对话，情景问答

补全对话。

A: Good afternoon, Miller! l

B：I'm drawing a horse.

A:A horse? Can you let me have a look?

B: 2 . Here you are.

A: Oh, the horse looks very nice. Do you often draw in your free time?

B: 3 .

A: Do you like drawing?

B: Yes. I like drawing very much.

A: 4 ?

B: Because it's very interesting. And my art teacher is very kind to me.

A: 5 ?

B: I have an art lesson once a week.