度数自西向东增加的是__________经度，度数自北向南增加的是_______

The effect of the baby boom on the schools helped to make possible a shift in thinking about the role of public education in the 1920’s. In the 1920’s, but especially (1) the Depression of the 1930’s, the United States experienced a (2) birth rate. Then with the prosperity (3) on by the Second World War and the economic boom that followed it, young people married and (4) households earlier and began to (5) larger families than had their (6) during the Depression. Birth rates rose to 102 per thousand in 1946, 106.2 in 1950, and 118 in 1955. (7) economics was probably the most important (8) , it is not the only explanation for the baby boom. The increased value placed (9) the idea of the family also helps to (10) this rise in birth rates. The baby boomers began streaming (11) the first grade by the mid-1940’s and became a (12) by 1950. The public school system suddenly found itself (13) The wartime economy meant that few new schools were buih between 1940 and 1945. (14) , large numbers of teachers left their profession during that period for better-paying jobs elsewhere.

(15) , in the 1950’s, the baby boom hit an antiquated and inadequate school system. Consequently, the custodial rhetoric of the 1930’s no longer made (16) ; keeping youths ages sixteen and older out of the labor market by keeping them in school could no longer be a high (17) for an institution unable to find space and staff to teach younger children. With the baby boom, the focus of educators (18) turned toward the lower grades and back to basic academic skills and (19) . The system no longer had much (20) in offering nontraditional, new, and extra services to older youths.

4().

A. adopted

B. incorporated

C. administered

D. established

我国中科院上海生化所于1982年5月合成了一种具有镇痛作用而又不会像吗啡那样使病人上瘾的药物--脑啡肽，下面是它的结构简式。请根据此化合物的结构分析回答下列问题：

(1)该化合物有 __________个氨基和___________个羧基。

(2)该化合物是由_______个氨基酸失去 ______分子水而形成的，这样的反应叫作_______，该化合物叫________肽。

(3)该化合物有__________种氨基酸构成，造成氨基酸种类不同的原因是__________。

根据《国家环境保护总局建设项目环境影响评价文件审批程序规定》，按照国家规定实行审批制的建设项目，建设单位应当在( )报批环境影响评价文件。

A．报送可行性研究报告前

B．提交项目申请报告前

C．办理备案手续后和开工前

D．开工前

()就是股票发行和交易的场所，由股票发行市场和股票流通市场两个层次构成。

A．证券交易所

B．股票市场

C．证券市场

D．债券市场

甲、乙、丙三人的步行速度分别为3.1km/h、64m/h和1m/s．则三人的速度由大到小的关系是______．（v_甲、v_乙、v_丙表示）