元朝剧作家关汉卿的代表作是（     ）

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Hello! I'm Jane from Canada. I like my school a lot. It's not big 1 it's very nice. All my teachers and classmates are 2 to me. I love3 very much. We study English, math, art and some other 4. Some subjects are  5, but some of them are boring. Of all of them, I like 6 best, because I like drawing pictures. Oh, my favorite 7 are Tuesday and Friday. On these     8 days, we have art lessons. I don't like politics 9 it's boring and difficult.

    My friend Susan 10 at my school. I often go to school with her. She likes politics. She thinks it's easy.

有关a、b两种物质的溶解度曲线如图所示，下列叙述不正确的是（　）

已知奇函数y=f（x）的导函数f′（x）＜0在R恒成立，且x，y满足不等式f（x²﹣2x）+f（y²﹣2y）≥0，则$\sqrt{x^2+y^2}$的取值范围是（　　）