The best way to explain how this procedure is expected to work is to explain how it actually worked when it was first tried. The first experiment with it was the creation of the Works Project Administration (WPA). This agency set up work projects in various fields in which there were many unemployed. For example, unemployed actors were organized into theater projects, orchestras were organized for unemployed musicians, teaching projects for unemployed teachers, and even writers' projects for unemployed writers. Unemployed laborers were put to work building or maintaining roads, parks, playgrounds, or public buildings. These were all temporary "work relief" projects rather than permanent work opportunities.
More substantial work projects of a permanent nature were organized by another agency, the Public Works Administration (PWA). This agency undertook the planning of construction of schools, houses, post offices, dams, and other public structures. It entered into contracts with private construction firms to erect them, or it loaned money to local or state governments which undertook their construction. This created many jobs in the factories producing the material as well as in the projects themselves, and greatly reduced the number of unemployed.
Still another agency which provided work projects for the unemployed was the Civilian Conservation Corps (CCC). This agency provided job opportunities for youths aged 16 to 20 to work in national parks or forests clearing land, guarding against fires, building roads, or doing other conservation work. In the event of a future depression, the federal government might revive any or all of the above methods to relieve unemployment and stimulate business.
The PWA differed from the WPA in that the ______.
A.letters were reversed
B.work projects of the former were carded ont by the Federal government
C.government subsidized private industry
D.number of unemployed was reduced
第2题
关于哺乳动物长期致癌试验的叙述,不正确的是
A.常用动物有大鼠和小鼠
B.实验期限大鼠为2年,小鼠为1.5年
C.常设3个剂量组和阴性对照组,高剂量组剂量应为最大耐受剂量(MTD)
D.每组雌雄各10只动物
E.结果观察主要指标是肿瘤发生的数量和性质
第3题
哺乳动物长期致癌试验的叙述,不正确的是
A.常用大鼠和小鼠
B.常设3个剂量组和阴性对照组,高剂量组剂量应为最大耐受剂量
C.每组雌雄动物各10只
D.动物实验期限大鼠为2年,小鼠为1.5年
E.主要观察指标是肿瘤发生的数量和性质
第4题
A.阴性对照组出现一种或数种肿瘤,实验组肿瘤发生率更高,且存在剂量反应关系
B.用两个物种开展的试验,其中一个物种结果为阳性,一个为阴性
C.试验组出现的肿瘤类型比对照组多,且存在剂量反应关系
D.试验组发生肿瘤的时间比对照组早,且存在剂量反应关系
第5题
阳性结果可确定哺乳动物致癌物,阴性结果不能否定对哺乳动物致癌性,这类试验是
A.哺乳动物长期致癌试验
B.致突变试验,恶性转化试验
C.哺乳动物短期致癌试验
D.构效关系分析
E.流行病学调查
第6题
A.哺乳动物长期致癌试验(终生试验)
B.啮齿动物长期致癌试验(一年试验)
C.无脊椎动物长期致癌试验(三年试验)
D.哺乳动物长期致痛试验(五年试验)
E.哺乳动物长期致痒试验(长期试验)
F.哺乳动物长期致瘤试验(长期试验)
第7题
哺乳动物长期致癌试验中,动物的选择错误的是()
A、在选择物种和品系时,应考虑自发肿瘤率
B、选用性成熟的动物
C、每组动物较一般毒性试验多
D、一般雌雄各半
E、每组动物数一般为雌雄各50只
第8题
阳性结果可确定哺乳动物致癌物,阴性结果不能否定对哺乳动物致癌性,这类试验是
A.肿瘤流行病学调查
B.致突变试验,恶性转化试验
C.恶性转化试验,哺乳动物短期致癌试验
D.哺乳动物短期致癌试验
E.哺乳动物长期致癌试验
第9题
B、设置3个剂量组、1个对照组,必要时设1个溶剂对照组;试验期限要求长期或终生
C、选用成年动物
D、观察指标常用的为肿瘤发生率、多发性、潜伏期
E、尽量选择自发肿瘤率低的动物;每组动物数较一般毒性多,常为雌雄各50只
判别化学致癌物应包括的证据A、器官水平证据
B、细胞学证据
C、组织水平证据
D、人群流行病学调查以及动物实验证据
E、人体接触水平
常用的试验方法不包括A、致突变试验
B、细胞转化试验
C、哺乳动物短期致癌试验
D、慢性毒性试验
E、哺乳动物长期致癌试验
无法检出的物质是A、遗传毒性致癌物
B、非遗传毒性致癌物和遗传毒性非致癌物
C、非遗传毒性非致癌物
D、致突变物
E、间接致突变物
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