线弹性平面弯曲时,中性轴通过横截面()。
A.重心
B.质心
C.弯心
D.形心
参考答案:D
胎盘早剥的临床和超声表现,下列哪一项是错误的()。
A.妊娠晚期 * * 出血
B.胎盘覆盖宫颈内口
C.分为胎盘后与边缘出血
D.可导致早产、胎儿死亡
E.系底蜕膜出血,形成血肿
If our government attention to controlling food safety now, our health ________ in danger.
A.won't pay; is
B.doesn't pay; is
C.won't pay; will be
D.doesn't pay; will be