田柴科制度

血浆半衰期最长的强心苷

A．地高辛
B．洋地黄毒苷
C．米力农
D．多巴酚丁胺
E．毒毛花苷K

采用升降车作业时，应两人进行，一人（），一人（），升降车应可靠接地。

A.指挥

B.作业

C.旁站

D.监护

E.负责

下列符合离心鼓风机的清洗和检查要求的有（）。

A、出厂已装好的机壳垂直中分面不应拆卸清洗；筒型结构机器的清洗，应符合随机技术文件的规定

B、扩压器和回流器组成一体的隔板、与机壳固定在一起的轴承箱等在清洗时不应拆卸

C、润滑油系统不应拆卸清洗

D、带调整垫结构和旋转结构的组件拆洗时应做好标记，并不得互换组别或位臵

Electrical engineers have repeatedly demonstrated that the best solid-state amplifiers are indistinguishable from the best vacuum-tube amplifiers with respect to the characteristics commonly measured in evaluating the quality of an amplifier’s musical reproduction. Therefore, those music lovers who insist that recorded music sounds better when played with the best vacuum-tube amplifier than when played with the best solid-state amplifier must be imagining the difference in quality that they claim to bear.
Which one of the following, if true, most seriously weakens the argument

A．Many people cannot tell from listening to it whether a recording is being played with a very good solid-state amplifier or a very good vacuum-tube amplifier.

B．The range of variation with respect to the quality of musical reproduction is greater for vacuum-tube amplifiers than for solid-state amplifiers.

C．Some of the characteristics that are important in determining how music sounds to a listener cannot be measured.

D．Solid-state amplifiers are more compact, use less power, and generate less heat than vacuum-tube amplifiers that produce a comparable volume of sound.

E．(E) Some vacuum-tube amplifiers are clearly superior to some solid-state amplifiers with respect to the characteristics commonly measured in the laboratory to evaluate the quality of an amplifier’s musical reproduction.

两合同型号的离心泵并联工作时，总扬程等于（）.

A.单泵扬程

B.两泵扬程之和

C.两泵扬程之差

D.两泵扬程的