初产妇，孕39周，宫缩较强，第三产程20分钟，总产程3小时，胎儿娩出后即开始有鲜红血流出，5分钟后胎盘自然娩出， * * 出血仍多，色鲜红，有血块，估计出血的可能原因是（）

A.宫缩乏力

B.胎盘残留

C.凝血功能障碍

D.血管损伤

E.宫颈裂伤

17. -- My mother always tells me to try my best _______ many difficulties.

-- I can’t agree any more. _______ you put your heart into work, you can overcome them.

A．because of / As far as

B．due to / As soon as

C．in spite of / As long as

D．despite of / As much as