剖宫产切口裂开出血的特点是：
A．突然发生
B．无痛性
C．大量出血
D．可以反复发生
E．患者多合并贫血和休克
参考答案：A,B,C,D,E
The experts were doing their experiment in the lab, ______ what happened outside. [ ]
A. didn't know
B. not knew
C. not knowing
D. having not known
