地下室材料防水构造主要有（）几种。 A.卷材防水 B.刚性防水 C.砂浆防水 D.涂

烤瓷金属基底桥连接体的位置，较金属桥连接体的位置略偏（）。

A.近中

B.远中

C.舌侧

D.颊侧

E.龈底

--Ann acts quite unfriendly.  ---I think she’s ___ than unfriendly.

A．shyer

B．shy

C．rather shy

D．more shy

阅读下列科普短文，然后回答问题．

臭氧的化学式是O₃，在通常状况下是淡蓝色、有鱼腥臭味的气体．臭氧不稳定，一旦受热极易转化成O₂，并放出大量的热，臭氧的氧化能力比氧气（O₂）强得多．若将O₂通过臭氧发生器，在无声放电条件下，从臭氧发生器出来的O₂中含有3%的O₃．臭氧在地面附近的大气层中含量极少，在离地面25千米处有一个厚度极薄的臭氧层．臭氧层能吸收太阳辐射的大量紫外线，使地球上的生物免遭紫外线的伤害．它是一切生命的保护层．超音速飞机排出的废气中的一氧化碳（CO）、二氧化硫（SO₂）、一氧化氮（NO）等气体、家用电冰箱中使用的制冷剂“氟里昂”等对臭氧层有很大的破坏作用，会使臭氧层形成空洞，从而使更多的紫外线照射到地球表面，导致皮肤癌的发病率大大增加，如不采取措施，后果不堪设想．

（1）臭氧的物理性质是______．

（2）将带火星的木条伸入到盛有O₃的集气瓶中，可以看到______的现象．

（3）写出在臭氧发生器中，O₂转变为O₃的文字表达式______．氧气转变成臭氧的过程发生______变化（填“物理“或“化学“）．

（4）应采取______的方法保护臭氧层．

（5）二氧化硫（SO₂）遇到O₃微热，即被迅速氧化成三氧化硫（SO₃），SO₃跟水反应生成硫酸，这是除去废气中SO₂的理想方法．写出SO₂ 与O₃反应的文字表达式______．该反应的基本反应类型是______反应，从物质与氧结合的角度看是______反应．

什么是扩频？扩频系统是如何提高抗干扰能力的？

In a perfectly free and open market economy, the type of employer -- government or private -- should have little or no impact on the earnings differentials between women and men. However, if there is discrimination against one sex, it is unlikely that the degree of discrimination by government and private employers will be the same. Differences in the degree of discrimination would result in earnings differentials associated with the type of employer. Given the nature of government and private employers, it seems most likely that discrimination by private employers would be greater. Thus, one would expect that, if women are being discriminated against, government employment would have a positive effect on women’s earnings as compared with their earnings from private employment. The results of a study by Fuchs support this assumption. Fuchs’s results suggest that the earnings of women in an industry composed entirely of government employees would be 14. 6 percent greater than the earnings of women in an industry composed exclusively of private employees, other things being equal.

In addition, both Fuchs and Sanborn have suggested that the effect of discrimination by consumers on the earnings of self-employed women may be greater than the effect of either government or private employer discrimination on the earnings of women employees. To test this hypothesis, Brown selected a large sample of White male and female workers from the 1970 Census and divided them into three categories: private employees, government employees, and self-employed. (Black workers were excluded from the sample to avoid picking up earnings differentials that were the result of racial disparities. ) Brown’s research design controlled for education, labor-force participation, mobility, motivation, and age in order to eliminate these factors as explanations of the study’s results. Brown’s results suggest that men and women are not treated the same by employers and consumers. For men, self-employment is the highest earnings category, with private employment next and government lowest. For women, this order is reversed.

One can infer from Brown’s results that consumers discriminate against self-employed women. In addition, self-employed women may have more difficulty than men in getting good employees and may encounter discrimination from suppliers and from financial institutions.

Brown’s results are clearly consistent with Fuchs’s argument that discrimination by consumers has a greater impact on the earnings of women than does discrimination by either government or private employers. Also, the fact that women do better working for government than for private employers implies that private employers are discriminating against women. The results do not prove that government does not discriminate against women. They do, however, demonstrate that if government is discriminating against women, its discrimination is not having as much effect on women’s earnings as is discrimination in the private sector.

It can be inferred from the text that what is stated in the last paragraph is most probably（）

A. Brown’s elaboration of his research results

B. Brown’s tentative inferences from his data

C. Brown’s conclusions based on common-sense reasoning

D. the author’s conclusion, based on Fuchs’s and Brown’s results