脑栓塞的栓子最常见的来源是（）
A.心脏瓣膜赘生物或左心房附壁血栓
B.脂肪栓子
C.空气栓子
D.肺静脉血栓
E.下肢静脉血栓
参考答案：A
The novel written by the author best, but five years ago no one could have imagined how great a role he in the literary world.
A．sell;was to play
B．selling ;was playing
C．sold ;had played
D．sell;is playing
14—16世纪的欧洲发生了巨大的变化。导致这一变化的根本原因是[ ]
A．文艺复兴运动的兴起
B．古希腊．罗马文明的推动
C．新航路的开辟
D．商品经济与资本主义萌芽的发展
