血清AFP升高可见于下列情况，但须除外哪项
A．原发性肝癌B．原发性胆汁性肝硬化C．妊娠D．慢性活动性肝炎E．生殖腺胚胎癌
参考答案：B
Woman: Is the rescue crew still looking for survivors of the plane crashMan: Yes, they have been searching the area for hours, but they haven't found anybody else. They'll keep searching until night falls.Question: What do we learn from the conversation
A．All the passengers were killed.
B．The plane crashed in the night.
C．No more survivors have been found.
D．It's too late to search for survivors.
F级燃机转子有两种形式，一种为外围拉杆螺栓连接的盘鼓式结构，其它级通过（）根外围拉杆连接，另一种为中心拉杆。
A、8
B、10
C、12
