搜题请搜索小程序“爱下问搜题”
问题 选择题

如图各容器中盛有海水，铁在其中被腐蚀时，由快到慢的顺序是（　　）

A．4＞2＞1＞3

B．2＞1＞3＞4

C．4＞2＞3＞1

D．3＞2＞4＞1

答案

根据图知，（2 ）、（3）装置是原电池，（ 4）装置是电解池；

（2 ）装置中铁作负极，很容易失电子变成离子进入溶液，促进铁腐蚀的速度；

（ 3）装置铁作正极，锌易失电子而使铁受到保护，抑制铁腐蚀的速度；

（4）装置中铁作阳极，在外加电源的作用下，腐蚀速度最快；

（ 3）装置铁受到保护，（1）装置铁的反应速度未受到保护也未受到抑制，所以（ 1）中铁的腐蚀比（3）中的快．

故答案为：（4）＞（2）＞（1）＞（3）

判断题

对于保护支路与配合支路成环行网络，正序助增系数与故障类型无关
查看答案
单项选择题

Rapid advances in computer and communication technologies have resulted in the (58) merger of these two fields. The lines have bluned among computing, switching, and digital transmission equipment, and the same digital techniques are being used for data, voice, and image transmission. Merging and evolving technologies, coupled with increasing demands for efficient and timely collection, processing, and (59) of information, are leading to the development of (60) that transmit and process all types of data. The ultimate goal of this evolution is something its proponents-some of the most powerful forces in the computing and telecommunications industries-call the (61) .The (61) will be a worldwide public telecommunications network that will deliver a wide variety of services. The (61) will be defined by the standardization of user interfaces, and will be implemented as a set of digital switches and paths supporting a broad range of traffic types and providing (62) processing services. Inpractice, there will be multiple networks, implemented within national boundaries, but from the user’s point of view there will be a single, uniformly accessible worldwide network.

Rapid advances in computer and communication technologies have resulted in the（）merger of these two fields.

A．decreasing

B．increasing

C．collective

D．single
查看答案