与前置胎盘发生无关的是（）
A.妊娠期高血压疾病
B.双胎妊娠
C.多次刮宫
D.胎盘面积过大
E.受精卵滋养层发育迟缓
参考答案：A
of the household garbage recycled or reused since the new technology was applied.
A．Three-fourth; has
B．Three-fourths; have
C．Three-fourths; has been
D．Three-fourth; have been
影响铁矿石还原性的主要因素有（）、（）、（）、（）等。
