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问题 选择题

为预防猪流感传染给人，2009年11月16日，我市甲型H1N1流感疫苗接种工作正式启动．你认为疫苗和预防接种分别属于（　　）

A．抗原，非特异性免疫

B．抗原，特异性免疫

C．抗体，非特异性免疫

D．抗体，特异性免疫

答案

由分析可知给同学们大多接种了甲型H1N1流感疫苗是由病原体制成的，只不过经过处理之后，其毒性减少或失去了活性，但依然是病原体，进入人体后不会使人得病，但能刺激免疫细胞产生相应的抗体，则这种疫苗相当于抗原；其产生的抗体只对甲型H1N1流感病毒起作用，对其它病原体无效，因此属于特异性免疫．

故选B．

单项选择题

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.

9().

A. at

B. on

C. for

D. with
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填空题

挤压类手法包括______、______、______、 ______等手法。
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