收录机等小型家用电器所用的稳压电源,是将220V的正弦交流电变为稳定的直流电的装

题型:选择题

问题:

收录机等小型家用电器所用的稳压电源,是将220V的正弦交流电变为稳定的直流电的装置,其中的关键部分是整流电路,有一种整流电路可以将正弦交流电变成如图所示的脉动直流电(每个“脉动”都按正弦规律变化),则此脉动电流的有效值为(  )

A.8 A

B.4 A

C.8A

D.4A

考点:交变电流的周期和频率交变电流的最大值、有效值、瞬时值和平均值
题型:选择题

只要肯动脑,写句难不了。

 1.小女孩拾起贝壳。   (把句子写具体些) 

                                                                             

2.我摇动着爱尔莎的乳牙。(不改变句意)

    换一种说法:                                                                                 

例:这不恰好表明有数不尽的骆驼吗?   

       这恰好表明有数不尽的骆驼。 

3.这不正说明他是一个肯动脑的好学生吗?  

                                                                                                          

4.翠鸟背上的羽毛像浅绿色的外衣。  

                                                                                                          。

题型:选择题

辛某,女,60岁,因肺心病收住院治疗,护士巡视病房时,发现病人口唇紫绀,血气分析结果显示:PaO25.6kPa,PaCO29.3kPa。

护士为病人提供的用氧方式是()。

A.低流量,高浓度持续给氧

B.低浓度,高浓度持续给氧

C.低流量,低浓度持续给氧

D.低流量,低浓度间断给氧

E.高流量,高浓度间断给氧

题型:选择题

近日《四川日报》报道,“2011年11月1日上午9时40分,沐川金王寺水库成功截流…”该项目是一座以灌溉、城乡供水为主,兼顾防洪等综合利用的中型水利工程,预计2014年建成.对此有下述认识,你认为错误的是(  )

A.建成后诸如沐川县城局部地区、个别学校开学初出现用水问题的状况将达到很大程度的改善

B.用肥皂水区分该水库里的水是硬水还是软水,若是软水就可不经净化而直接饮用

C.在生活中不用含磷洗衣粉,生产中合理使用化肥、农药,以减少对水质的污染

D.水是人类赖以生存的自然资源,我们仍需节约用水和合理开发利用水资源

题型:选择题

Information systems design is defined as those tasks that focus on the specification of a detailed computer-based solution. Typically, there are four systems design tasks for in-house development. 1)The first task is to specify (1), which defines the technologies to be used by one, more, or all information systems in terms of their data, processes, interfaces, and network components. This task is accomplished by analyzing the data models and process models that are initially created during requirements analysis. 2)The next systems design task is to develop the (2). The purpose of this task is to prepare technical design specifications for a database that will be adaptable to future requirements and expansion. 3)Once the database prototype has been built, the systems designer can work closely with system users to develop input, output and dialogue specifications. The (3) must be specified to ensure that the outputs are not lost, misrouted, misused, or incomplete. 4)The fourth design task involves packaging all the specifications from the previous design tasks into a set of specifications that will guide the (4) activities during the following phases of the systems development methodology. Finally, we should (5) and update the project plan accordingly. The key deliverable should include a detailed plan for the construction phase that should follow.

空白(2)处应选择()

A.database design specifications

B.database organization decisions

C.data structure specifications

D.data distribution decisions

题型:选择题

教育心理学作为独立学科诞生的标志是( )。

A.1877年卡普杰列夫的《教育心理学》

B.1886年霍普金斯的《教育心理学》

C.1899年詹姆斯的《对教师的谈话》

D.1903年桑代克的《教育心理学》

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