某口袋中装有红色、黄色、蓝色三种颜色的小球（小球出颜色外完全相同）共60个．通过多次摸球实验后，发现摸到红球、黄球的频率分别是30%和45%，由此估计口袋中蓝球的数目约为____ 个．

某种酶是由419个氨基酸形成的蛋白质。科学家利用生物技术做出5种不同长度的该酶的片段，并分别测定其活性如图所示，分析该酶最可能具有活性的部分是(　　)                                                          

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山野中，那蓬苇草

    ①苇草在深秋的原野上，悠然而淡泊。

    ②第一次看到苇草是到乡下去看外婆。外婆作为我人生理想的启蒙者，就像山间的茅舍和青石板小路一样，使我感到持久的宁静和亲切。

    ③很小的时候，我就依偎在外婆的臂膀里，听她讲述《聊斋》和许多关于仙女侠客的故事。那是山间静寂的夜晚，一盏煤油灯在外婆饱经世间沧桑的脸庞上闪动；外婆倚在床头，一边吧嗒着叶子烟，一边向我讲神仙鬼怪，我就在外婆娓娓动听的叙述中进入了童年的甜梦。

    ④我是和外婆一起去田野中采摘名叫侧耳根的野菜时见到苇草的，不过当时是燠热的夏天。苇草就长在池塘四周的塘坎上。池塘背后便是一座长满了青杠和灌木的小山丘，里间有甲虫、蜗牛、蟋蟀等让我极感兴趣的昆虫，每年春夏长满了各类野生菌，当然树林里也有毒蛇出入，所以那山丘于我一直是一个大神秘。外婆是小脚，属于严格意义的三寸金莲。苇草在夏天油绿而蓬勃，其叶刚劲如矢。外婆放下菜篮，拆下一根苇叶，沿苇叶茎撕开两条小口，然后夹在拇指和食指之间，右手用力拉开茎两边的叶脉，茎便像箭矢般射向了天空。玩苇叶是我幼年最感快意的游戏。较之于外婆为我捕捉的蟋蟀和蚱蜢，更富于刺激因在拉开叶脉时稍不留意就会划伤手指。记得外婆第一次向我示范射苇叶时，脸上漾起了年轻的笑容，很慈祥亦很忘我。

    ⑤外婆是一个充满爱心的老人，对晚辈严谨而宽容。外婆所养老母鸡下的蛋除了换取家里必备的油盐，基本上全属于我了。尽管外婆的肺气肿极需营养，但她却从来就不舍不得自己吃。那时侯，农民难足温饱，日子很紧巴。打谷子季节我便跟在拌桶后面拾稻穗。黄昏，外婆便在低矮的屋檐下为我磨米做煎饼。外婆的煎饼只须少许几滴茶油，但总是香喷喷的。每当我和邻家小伙伴从高梁地汗涔涔回家时，外婆的煎饼已晾放在桌上了。

    ⑥外婆的纺车响在乡村宁静的长夜里。那单调绵长的纺线声几乎陪伴了我整个童年时期的梦境。很多很多年以后，那古老的纺车在故乡的油灯下永远消失了……但每次在静夜里听到鸡鸣犬吠，我就会不自觉地要去捕捉那悠远动听的纺车声。那是一首神秘而古朴的谣曲，弹拨着外婆和她的同辈辛勤艰苦的命运，美丽而必然的结局于现代文明的进程里。

    ⑦简易公路修到了外婆家门前。不久，外婆的一只老母鸡被汽车辗死了。她看见我舅舅把压碎了翅膀的老母鸡拣回来炖在锅里。那个晚上一家人显得很阴惨，外婆呆坐在饭桌上眼睛红红的，压根儿就没运过筷子。老母鸡的惨死使她伤心。我至今也领悟不到外婆对一只鸡的死为何表现出那样深郁的辛酸。不过那是一只被外婆唤来呼去，“咯咯咯”叫嚷不停老爱在外婆被窝里下蛋的老母鸡。那天的外婆很苍老，整个身体缩得极小，并且异常的不读小说不纺棉花便上床了。也许因为外婆内心很孤独对生命格外怜惜！

    ⑧外婆狠狠揍我是因为我偷摘了邻家玉米地的几支玉米。黄荆树在川南地区遍地皆是。外婆揍我的用的就是流着绿脂的荆条。外婆说：“做人要干净，偷鸡摸狗的事千万做不得。”外婆在我屁股抽打出的红痕上，像火像激情，至今仍燃在我心灵里。

    ⑨外婆在我5岁时就去世了。我守在外婆身边，听她讲完一生中最后一个故事。

    ⑩出殡的细节已不记得。舅舅们紧随在柏木棺材后面，头上包着白布和几丝苎麻。苇花已开了，那份黯然那份苍凉，在风中飘摇。太阳依然在山凹里悠闲地照着。

    ⑪外婆就葬在那蓬苇草旁。

— _______. I have a lot of homework to do.

    Your glasses may someday replace your smartphone, and some New Yorkers are ready for the switch. Some in the city can't wait to try them on and use the maps and GPS that the futuristic eyewear is likely to include.

    “ I'd use it if I were hanging out with friends at 3 a. m. and going to the bar and wanted to see what was open,” said Walter Choo, 40, of Fort Greene.

    The smartphone-like glasses will likely come out this year and cost between $250 and $600, the Times said, possibly including a variation of augmented(增强的) reality, a technology already available on smartphones and tablets (平板电脑) that overlays information onto the screen about one's surroundings. So, for example, if you were walking down a street, indicators would____showing you the nearest coffee shop or directions could be plotted out and come into view right on the sidewalk in front of you.

    "As far as a mainstream consumer product, this just isn't something anybody needs,” said Sam Biddle, who writes for Gizmodo.com.  “ We're accustomed to having one thing in our pocket to do all these things,” he added, “and the average consumer isn't gonna be able to afford another device (装置) that's hundreds and hundreds of dollars.”9to5Google publisher Seth Weintraub, who has been reporting on the smartphone-like glasses since late last year, said he is confident that this type of wearable device will eventually be as common as smartphones.

    “It's just like smartphones 10 years ago,” Weintraub said. “A few people started getting emails on their phones, and people thought that was crazy. Same kind of thing. We see people bending their heads to look at their smartphones, and it's unnatural,” he said. “ There's gonna be improvements to that, and this a step there.”