根据短文理解, 从A、B、C、D四个选项中选择正确答案填空。

    Mr. Smith 1 from London. Now he is in China. He is 2. He teaches 3 a middle school. He works very hard. His students like 4 very much. He can 5 a little Chinese. His students often teaches him Chinese 6 Sundays. Mr. Smith likes playing football. He often plays football 7 his students.

    Mr. Smith 8 a son. His name is Jack. He is student. He studies in a middle school. He goes to school 9 bike everyday. He gets back home at four in the afternoon. He likes 10 TV in the evening.

我们知道方程2x+3y=12有无数组解，但在实际生活中我们往往只需要求出其正整数解．例：由2x+3y=12，得 $y=\frac{12-2x}{3}=4-\frac{2}{3}x$ ，（x、y为正整数）∴ $\{\begin{array}{l}x>0\\ 12-2x>0\end{array}$ 则有0＜x＜6．又 $y=4-\frac{2}{3}x$ 为正整数，则 $\frac{2}{3}x$ 为正整数．

由2与3互质，可知：x为3的倍数，从而x=3，代入 $y=4-\frac{2}{3}x=2$ ．

∴2x+3y=12的正整数解为 $\{\begin{array}{l}x=3\\ y=2\end{array}$

问题：

【历史――选修1：历史上重大改革回眸】阅读材料，回答问题

材料：庙号改革是北魏孝文帝改革的一项重要内容。公元398年，拓跋珪迁都平城，仿中原传统制度设立太庙，早先草原部落联盟时代的首领以“太祖”“高祖”等庙号受到祭祀，他们的子孙被封为王公，享有政治军事特权，成为北魏政权的统治支柱。孝文帝下令改革庙号，宣称按“宗有功、祖有德”的原则，推最先实现在中原进行统治的拓跋珪为太祖，不再为拓跋珪以前的祖先设庙祭拜。因太祖拓跋珪以后只有五位皇帝去世，为了不违“天子七庙”这一儒家礼制，孝文帝甚至前无古人地在太庙中为自己虚设一庙。庙号改定后，孝文帝下令，“非太祖子孙”及异姓封王、公、侯、伯者，皆降一等。

——据吕思勉《魏晋南北朝史》