第8题: [单项选择]To minimize the bias in the selection of respondents, why was each respondent asked about their job role and supervisory responsibilities, their previous experience and working environment 参考答案:B
第9题: [单项选择]肾综合征出血热少尿期多发生于病程第几日() A. 第2~3日 B. 第4~6日 C. 第5~8日 D. 第9~14日 E. 第15~18日 参考答案:C