问题 问答题 简答题

牺牲阳极保护的工作原理是什么?

答案

参考答案:

在金属管道两部分之间存在电极电位差,在土壤中形成腐蚀电池,阳极处管路被腐蚀,带正电的金属离子由该处进入土壤。当在土壤中埋入一块电动势比钢铁高得多,即在土壤中的电极电位比管路金属低得多的外加金属与管路相连,即构成新的腐蚀系统。管路上各电极电位不同的部分相对于该处外加金属均构成了新腐蚀电池的阴极,因而电流将由该外加金属流入土壤,经土壤流入管路的各部分,再由管路经连接的导线返回外加金属,而构成回路。从而制止了管路上带正电的金属离子进入土壤,以保护管路免于腐蚀。而外加金属则成为阳极而不断地被腐蚀,故称为牺牲阳极。

单项选择题
单项选择题

Regardless of their political affiliation, in all countries women must overcome a host of stumbling blocks that limit their political careers. "Most obstacles to progress consist of (1) of various kinds," says the Inter-Parliamentary Union (IPU), a Geneva-based organization (2) 139 parliaments, including the lack of time, training, information, self-confidence, money, support, motivation, women’s networks and solidarity between women.

In every culture, prejudice and stereotypes (3) hard. The belief still holds (4) that women belong in the kitchen and (5) the children, not at election (6) or in the Speaker’s chair. The media often reinforce traditional images of women, who, upon entering politics, also bear the brunt (正面冲击) of verbal and physical (7) .

In impoverished (贫穷的) countries (8) by civil conflicts and deteriorating economic and social conditions, women are (9) by the tasks of managing everyday life and looking after their families.

The IPU stresses the general lack of child-care facilities—often (10) a privileged few—the (11) of political parties to change the times and running of meetings and the weak backing women receive from their families. That support, which is (12) as well as financial, is (13) vital because women have internalized (14) images of themselves since the (15) of time and often suffer from low self-confidence.

Another obstacle is the lack of financial resources, especially as election campaigns become increasingly expensive. (16) , women encounter more or less open machismo (男子汉的高傲) in the (17) of closed political circles (18) entry to the "second sex. " Lastly, they (19) the lack of solidarity between women, (20) by the fact that the number of available positions is limited.

3()

A.persist

B.vanish

C.revive

D.die