外伤致牙齿震荡后的治疗方案错误的是（）
A.消除咬合创伤
B.减少不良刺激
C.即刻根管治疗
D.预防感染
E.定期追踪复查
参考答案：C
The policeman's attention was suddenly caught by a small box which ______ placed under the Minister's car.
A．has been
B．was being
C．had been
D．would be
产后出血发生率占分娩总数的（）.
A.2％～3％
B.5％～6％
C.4％～5％
D.3％～4％
E.1％～2％
