下列实验方案能达到预期目的是（ ） ①实验室保存FeCl3溶液应加少量稀盐酸，并

"Popular art" has a number of meanings, impossible to define with any precision, which range from folklore to junk. The poles are clear enough, but the middle tends to blur. The Hollywood Western of the 1930’s for example, has elements of folklore, but is closer to junk than to high art or folk art. There can be great trash, just as there is bad high art. The musicals of George Gershwin are great popular art, never aspiring to high art. Schubert and Brahms, however, used elements of popular music--folk themes--in works clearly intended as high art. The case of Verdi is a different one: he took a popular genre-bourgeois melodrama set to music (an accurate definition of nineteenth-century opera) and, without altering its fundamental nature, transmuted it into high art. This remains one of the greatest achievements in music, and one that cannot be fully appreciated without recognizing the essential trashiness of the genre.
As an example of such a transmutation, consider what Verdi made of the typical political elements of nineteenth-century opera. Generally in the plots of these operas, a hero or heroine--usually portrayed only as an individual, unfettered by class--is caught between the immoral corruption of the aristocracy and the doctrinaire rigidity or secret greed of the leaders of the proletariat. Verdi transforms this naive and unlikely formulation with music of extraordinary energy and rhythmic vitality, music more subtle than it seems at first hearing. There are scenes and arias that still sound like calls to arms and were clearly understood as such when they were first performed. Such pieces lend an immediacy to the otherwise veiled political message of these operas and call up feelings beyond those of the opera itself.
Or consider Verdi’s treatment of character. Before Verdi, there were rarely any characters at all in musical drama, only a series of situations which allowed the singers to express a series of emotional states. Any attempt to find coherent psychological portrayal in these operas is misplaced ingenuity. The only coherence was the singer’s vocal technique: when the cast changed, new arias were almost always substituted, generally adapted from other operas. Verdi’s characters, on the other hand, have genuine consistency and integrity. Even if, in many casals, the consistency is that of pasteboard melodrama, the integrity of the character is achieved through the music: once he had become established. Verdi did not rewrite his music for differenf singers or countenance alterations or substitutions of somebody else’s arias in one of his operas, as every eighteenth-century composer had done. When he revised an opera, it was only for dramatic economy and effectiveness.

According to the text, Verdi’s creative treatment of characters is performed through

A．his frequent re-writing of an opera.

B．his coherent psychological portrayal.

C．his consistent aspiration to high art.

D．his effective maneuvers of music.

主要引起婴幼儿腹泻的轮状病毒是（）

A.A组人RV

B.D组人RV

C.E组人RV

D.C组人RV

E.B组人RV

关键个案抽样指的是选择那些可以对事情产生决定性影响的个案进行的研究。目的是将这些个案中获得的结果逻辑地推论至其他个案。
下列属于关键个案抽样的是( )。

A．对所有购买产品的顾客进行电子邮件调查以了解产品可以从哪些方面进行改进

B．对若干6岁儿童进行访问以剔除专门为6岁儿童开发但不受欢迎的糖果口味

C．制定严格的电话抽样方案，要求调查员电话访问顾客搜集对产品包装的反馈

D．在居民区中随机寻找符合产品香味调查的对象，邀请测试完成一份调查问卷

违反《公路水运工程试验检测管理办法》被注销考试合格证书的检测人员1年内不得再次参加考试。

电梯的安全装置中，防人员剪切和坠落的保护装置的安全标准要求不正确的是( )。

A．当轿门和层门中任一门扇未关好和门锁未啮合5mm以上时，电梯不能启动

B．当电梯运行时轿门和层门中任一门扇被打开，电梯应立即停止运行

C．当轿厢不在层站时，在站层门外不能将层门打开

D．紧急开锁的钥匙只能交给一名负责人员，只有紧急情况下才能由专业人员使用