患儿，男，10岁，因右下后牙冷、甜刺激酸痛1周就诊。提示：右下第一磨牙热活力测试中一

Ragtime is a musical form that synthesizes folk melodies and musical techniques into a brief quadrille-like structure, designed to be played--exactly as written--on the piano. (46) A p analogy exists between European composers like Ralph Vaughan Williams and Edward Grieg, who combined folk tunes and their own original materials in larger compositions and the pioneer composers in the United States. Composers like Scott Joplin and James Scott were in a sense collectors or musicologists, collecting dance and folk music in Black communities and consciously shaping it into brief suites or anthologies called piano rags.

It has sometimes been charged that ragtime is mechanical. For instance, Wilfred Mellers comments, "rags were transferred to the pianola roll and, even if not played by a machine, should be played like a machine, with meticulous precision. " (47) However, there is no reason to assume that ragtime is inherently mechanical simply because commercial manufacturers applied a mechanical recording method to it, the only way to record pianos at that date. Ragtime’s is not a mechanical precision, and it is not precision limited to the style of performance. It arises from ragtime’s following a well-defined form and obeying simple rules within that form.

The classic formula for the piano rag disposes three to five themes in sixteen-bar strains, often organized with repeats. (48) The rag opens with a bright, memorable strain or theme, followed by a similar theme, leading to a melody of marked lyrical character, with the structure concluded by a lyrical strain that parallels the rhythmic developments of the earlier themes. The aim of the structure is to rise from one theme to another in a stair-step manner, ending on a note of triumph or exhilaration. Typically, each strain is divided into two 8-bar segments that are essentially alike, so the rhythmic-melodic unit of ragtime is only eight bars of 2/4 measure. (49) Therefore, not concerned with development of musical themes, the ragtime composer instead sets a theme down intact, in finished form, and links it to various related themes that are brief with clear melodic figures. Tension in ragtime compositions arises from a polarity between two basic ingredients: a continuous bass--called by jazz musicians a boom-chick bass--in the pianist’s left hand, and its melodic, syncopated counterpart in the right hand. Ragtime remains distinct from jazz both as an instrumental style and as a genre. Ragtime style stresses a pattern of repeated rhythms, not the constant inventions and variations of jazz. (50) As a genre, ragtime requires strict attention to structure, not inventiveness or exceptional skills, existing as a tradition, a set of conventions, a body of written scores, separate from the individual players associated with it. In this sense ragtime is more akin to folk music of the nineteenth century than to jazz.

(47) However, there is no reason to assume that ragtime is inherently mechanical simply because commercial manufacturers applied a mechanical recording method to it, the only way to record pianos at that date.

唐朝和西汉相似的地方是

①开国皇帝都是吸取前王朝灭亡的教训②两朝都出现过治世局面

③两朝都有与周边少数民族和亲的历史④都成都在长安[ ]

A．①②③④

B．①②③

C．①③

D．②③

属于皮质淋巴窦的是（）。

A、被膜下淋巴窦

B、小梁周窦

C、边缘窦

D、髓窦

女性，42岁，主因咳嗽、胸骨后不适1月余来院就诊，胸片示中纵隔气管旁4cm×4cm肿物，界限清楚，表面光滑，无分叶毛刺，密度均匀，无钙化。

明确诊断的最简单的检查方法为（）。

A.胸部增强CT检查

B.胸部MRI检查

C.胸部PET检查

D.胸部超声检查

E.纤维支气管镜检查

下列果实和种子中可借风力传播的是（）。

A.莴苣

B.棉花

C.苍耳

D.鬼针草

E.榆

F.凤仙花