下列哪项因素与发病率的变化无关（）。
A.致病因素的作用明显加强和减弱
B.患病率的升高或下降
C.疾病诊断水平的提高或下降
D.诊断标准的变化
E.防疫措施的有效与否
参考答案：B
解析：发病率指一定期间内，一定人群中某病新发生的病例出现的频率，而患病率是指某特定时间内一定人群中某病新旧病例所占的比例。因此，患病率的升高或降低与发病率的变化无关。
| 从方框中选择正确的疑问词将句子补充完整。 | |
— I usually go to school by bike. 2. — ____________ is the science museum? — It's next to the cinema. 3. — ____________ are you going to do this weekend? — I'm going to visit my grandparents. 4. — ____________ do you go to the library every Sunday? — Because I like reading books very much. 5. — ____________ is going to take a trip next week? — My father is. |