问题 问答题 简答题

水轮机汽蚀侵蚀的特征是什么?

答案

参考答案:

(1)侵蚀区的金属表面呈海绵状针孔,表面有呈灰暗无光泽的大小蜂窝及透孔;

(2)金属疏松脱落。若表面覆盖有抗蚀材料,汽蚀侵蚀会绕过表面抗蚀覆盖层,而在底层母材上深入发展;

(3)侵蚀破坏一般在叶片背面发生。

阅读理解

Pregnancy(妊娠) and childbirth kill more than 536,000 women a year. More than half of the cases happened in Africa, according to the World Health Organization. In fact, most of the deaths are preventable with basic medical care.

The five leading causes are bleeding, infection, high blood pressure, long­time labor and bad abortions (流产). Mothers' deaths from such causes were largely reduced nearly a century ago in developed countries.

Experts say that what kill many women are “the three delays”— the woman's delay in deciding to go to the hospital, the time she loses traveling there and the hospital's delay in starting treatment. Only about 15 percent of births have dangerous complications(并发症).

Women lack education and information about birth control. Husbands and in­laws, may decide where a woman gives birth and insist that she stay at home to save money. However, there is no single solution to a problem with so many factors—shortages of doctors, nurses, drugs, equipment, roads and transportation—though hospital officials are trying many things now.

One stopgap measure to solve the problem for the present has been to train assistant medical officers, to perform certain operations. Some African countries are now struggling to train more assistants and midwives (接生婆) , and provide places for pregnant women to stay near hospitals.

But there is a long way to go. Only 20 percent of women in the continent give birth at the hospital. More than 50 percent stay at home to give birth, and the rest go to local clinics that cannot handle emergencies.

小题1:Which is not included in the five leading causes of women's deaths during pregnancy and childbirth?

A.Infection.

B.High blood pressure.

C.Traveling long distances.

D.Bleeding.小题2:The underlined word “stopgap” probably means “________ ”in the passage.

A.final

B.temporary

C.effective

D.instant小题3:What can we learn from this passage?

A.The governments of African countries have to take more effective measures to save pregnant women.

B.Developed countries should help African countries reduce mothers'deaths.

C.The husbands in poor countries should take responsibility for their wives'deaths.

D.Most problems that cause women's deaths during pregnancy and childbirth can be treated or prevented.小题4:What is the author's attitude towards the future of preventing women's deaths during pregnancy and childbirth?

A.Positive.

B.Negative.

C.Objective.

D.Subjective.

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