马钱子对中枢神经系统的药理作用是()
A、兴奋脊髓的反射功能
B、抑制脊髓的反射功能
C、兴奋血管运动中枢
D、抑制血管运动中枢
E、兴奋呼吸中枢
参考答案:A, C, E
Our teacher asked me ________.
A.what was Ann doing these days
B.why didn’t Peter come to school the day before
C.when will the dolphin show begin
D.how long I usually spent on my homework
定群研究中暴露组发病率与非暴露组发病率的比值为
A.相对危险度
B.比值比
C.归因危险度
D.归因危险度百分比
E.人群归因危险度