前置胎盘产后大出血的原因是（）。
A.胎盘植入
B.子宫下段收缩力弱
C.凝血功能障碍
D.子宫下段易撕裂
E.产后未使用缩宫素
参考答案：B, D
------“The Leaning Tower of Pisa must be saved, __________ the cost.”
------“But Italy is now deep in the European Debt Crisis. It would be unlikely __________ its government hoped to ”
A．however, even though
B．whatever, even if
C．whoever, as if
D．whichever, as though
职业性致癌物包括（）。
A.确认致癌物
B.可疑致癌物
C.潜在致癌物
D.动物致癌物
E.A、B、C三项
