子宫脱垂的常见病因有______、______、______。
参考答案：分娩时损伤和产褥早期体力劳动；长期腹压增加；盆底组织先天性发育不良或退行性变
许多场所或产品的外包装常有一些标志,下列图标中属于物品回收标志的是[ ]
A.
B.
C.
D.
My goodness. How lucky we are! If there had been places for us on that aero-plane, we ________dead now.
A．will be
B．would be
C．would have been
D．had been
