临床上病理性缩复环最多见于哪种情况()
A．胎盘早剥
B．前置胎盘
C．头盆不称
D．低张性宫缩乏力
E．胎儿窘迫
参考答案：C
写出这些颜色。
1. The tree is ___________ in summer. (夏天)
2. The orange is ___________.
3. The blackboard is ___________.
4. The sun is ___________ in the morning.
为了保护转化催化剂，停工时怎样操作？
