调查某市甲型肝炎爆发，分析时可选用指标
A．罹患率B．相对危险度C．有效率、副反应发生率D．抗体阳转率、效果指数E．患病率
参考答案：A
—You always go to the seaside and swim during the summer vacation. Don’t you want to try something different this year?
— .
A．Like what?
B．With pleasure .
C．Let’s go then.
D．That’s all right.
镗床的用途、分类、机床运动。
