第2题: [单项选择]During the Middle Ages, productivity of labor ______. A. was a primary concern of society B. was hampered by class relationships C. began to improve over levels reached by the Greeks D. was in a period of technical progress 参考答案:B 答案解析:可在第四句话“The social system of fixed... the Middle Ages (and in some areas much longer) itself hampered
第3题: [单项选择]SARS－CoV在下列哪种细胞中培养滴度较高（） A. MDCK B. Vero－E6 C. RD D. 2SB E. 293 参考答案:B 答案解析:利用Veto－E6或Vero细胞很容易对SARS－CoV进行分离培养，细胞感染24小时即可出现病变。在RD、MDCK、293和2SB等细胞系上也可以培养但滴度较低。
第15题: [单项选择]What was the real purpose of the ruler’’s invitation A. To declare new ways of collecting tax. B. To entertain those who had made great contributions to the government. C. To collect money from the persons invited. D. To reward outstanding tax collectors. 参考答案:C
第19题: [单项选择]传染病的暴发流行是指 A. 在国内或地区内原来不存在，而从国外或外地传入的传染病 B. 发病率水平显著高于一般水平 C. 传染病病例发病地点的分布高度集中于一个区域之内 D. 传染病病例发病时间的分布高度集中于一个短时间之内 E. 某传染病的流行范围甚广，超出国界或洲界 参考答案:D
