下图是两组各$7$名同学体重（单位：$kg$）数据的茎叶图．设$1,2$两组数据的平均数依次为$\stackrel{-}{x_1}$和$\stackrel{-}{x_2}$，标准差依次为$s_1$和$s_2$，那么（    ）
（注：标准差$s=\sqrt{\frac{1}{n}{\left(x_1-\stackrel{-}{x}\right)}^2+{\left(x_2-\stackrel{-}{x}\right)}^2+\cdots +{\left(x_n-\stackrel{-}{x}\right)}^2}$，其中$\stackrel{-}{x}$为$x_1,x_2,\cdots ,x_n$的平均数）

著名学者牟宗三认为：“这套西周三百年的典章制度……到春秋的时候，就出现了问题，所以我们叫它做“周文疲弊”。诸子思想就是为了对付这个问题。”下列解决“周文疲弊”最具有针对性、现实性的思想是（  ）

阅读短文，根据短文内容，从所给的A.B.C.D.四个选项中选出最佳选项。

      People drink tea. There are many kinds of tea, such as black tea, green tea, white tea and yellow tea. People drink a lot of tea in China. Some people drink it because they think it makes them healthy. Many people drink it because it tastes very good. It is delicious.

      People drink a lot of tea in Japan. People drink a lot of green tea in South Korea, too. In Vietnam, people like to drink coffee first. Then they drink tea.

     People drink a lot of tea in England. Every afternoon, people drink tea. It's “tea time”. English people like to drink their tea with milk in it.

      Many people drink black tea in the US. In the South, people like to drink sweet tea. Sweet tea is cold black tea with sugar in it.

      Most tea comes from China. Some tea comes from India or Sri Lanka. Kenya, Japan and Indonesia also grow tea.

海水透明度是指用直径为30 cm的白色圆板，在阳光不能直接照射的地方垂直沉入水中，直到看不见的深度。下图为中国沿海夏季海水多年平均透明度等值线（单位：m）分布图。读图，完成下面小题。

A型(甲型)流感病毒，病毒极小，直径约100纳米，在冬季流行。A型病毒表面密布两种武器，血细胞凝集素(H)和神经氨酸苷酶(N)两种蛋白质。其中，H有16个亚型，N有9个亚型。二者组合不同，病毒的毒性和传播速度也不相同，A型病毒可以从野生动物传给家禽，家禽携带的病毒如果发生基因变异，可获得在人群中传染的能力。1997年在香港、2003年在荷兰、2005年在越南和泰国都出现了人类感染H5N1型禽流感病毒死亡的病例。下列叙述错误的是（  ）