三元触媒催化转换器在哪一空燃比时其净化效果最好。（）A.12.5：_爱下问搜题

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问题单项选择题

三元触媒催化转换器在哪一空燃比时其净化效果最好。（）

A.12.5：1

B.13.5：1

C.14.7：1

D.15.7：1

答案

参考答案：C

单项选择题

第1篇 Food for Learning

In Eritrea, a small country in northeast Africa, approximately 80 percent of the population is illiterate. That percentage is even higher in woman. As in many developing countries, many Eritreans have traditional ideas about the role of women. They believe that women should stay home and take care of the family and should not get an education or look for a job.
These beliefs are one of the factors that prevent Eritriea and other developing countries from improving their economic situation. Experience in many developing countries has shown that educated women have fewer children and have more opportunities for improving their lives and the lives of their families. In Eritrea, in fact, there is great need for improvement. It is one of the poorest countries in the world. For many Eritrean families, getting enough food is a daily problem.
To deal with these problems, the Eritrean government together with the World Food Program, has a new program that offers food as a reward for learning. In primary schools, all the children receive food packages to take home to their families. However, with the new program, the girls receive more food than the boys. This way, parents are encouraged to send their daughter to school rather than keeping them at home.
Another government program that aims to educate women is Food for Training. Managed by the National Union of Eritrean Women, this program offer food rewards (also from World Food Organization) to women and elder girls who are willing to join the program. Because of the war with Ethiopia, many women are bringing up their families on their own. They often live in refugee camps, with no land of their own and no way to earn money. Most of these women are illiterate and have no skills to find a job. They spend most of their day looking for food and preparing it for their families.
The Food for Training program helps the teenagers and women change their lives. If they agree to join the program, they receive a large package of food each month. In return, the women are required to attend free literate classes for two hours every day. When Food for Training classes in two regions of Eritrea, 5000 girls and women joined in the first two months. It is especially popular with teenage girls, aged fourteen to sixteen, who have never had a chance to go to school before.
The organizers of Food for Traing also plans to offer other kinds of courses for women, using the same system of food rewards. In these courses, they will teach women job skills and crafts such as basket weaving. These women will not only learn to read and write. They will become aware of what is going on in their country.

According to the passage, Food for Training will ______.

A．help women better their lives

B．encourage women to leave their country

C．teach women about international aid

D．allow women to spend more time at home

填空题

有意抽样法是指研究者按一定的（）去抽选样本。