测定尿雌三醇与肌酐(E/C)比值<______表明胎盘功能减退。
参考答案：10
I have _____ milk here. Would you like to drink some, Mark?
A few B little C a few D a little
为了避免高温和振荡的影响，引压管应远离（）
A、热源和电源
B、热源和振源
C、热源和空调
D、电磁场和振源
