绒癌除来源于葡萄胎外，还源于______、______及______。
参考答案：足月妊娠‖流产‖宫外孕
急性毒性试验一般要求观察
A．3天
B．5天
C．10天
D．14天
E．28天
Jenny is afraid of traveling by plane. She always looks _______ when she is getting on it. [ ]
A. neither
B. none
C. all
