劳动既是为个人谋生，也是为社会服务。( )

男，33岁。残冠，根尖病变。拔除过程中，远中颊根折断，取根时，牙根突然消失，捏鼻鼓气时拔牙窝内有气体逸出。

此时行X线检查首选的投照方法是（）。

A.头颅正位片

B.上颌侧位体层（磨牙列层）

C.头颅侧位片

D.全口曲面体层

E.华特位片

制作细菌染色标本时，干燥这一步骤如何去做？（）

A.火焰烤

B.自然干燥

C.风吹

D.紫外光照

E.超声波处理

形态理论中，三角形整理形态包括( )。

A．等腰三角形

B．对称三角形

C．上升三角形

D．下降三角形

阶层

Do p electric currents, by means of the electromagnetic fields that accompany them, cause cancer in people who live and work nearby Telephone line workers, who work near such currents every day, can provide a test case. They show elevated levels of brain cancer; therefore, the hypothesis of electromagnetic causation is supported.
Which of the following, if true, most seriously weakens the argument

A．Burying power lines and other measures to protect the public from such electromagnetic fields would be prohibitively expensive.

B．Telephone line workers are exposed to levels of chemical solvents high enough to cause brain cancer.

C．High exposure to p electromagnetic fields is correlated with a slightly higher-than-normal incidence of childhood leukemia, which is a form of cancer.

D．Public health officials who found that a group of different illnesses in people living near a power substation could not reliably be attributed to its electromagnetic field were accused of covering up the facts.

E．(E) Telephone line workers, like most people have electrical appliances at home, and most electrical appliances, when turned on, are surrounded by an electromagnetic field of some measurable level.