若脐带血循环阻断超过下述哪一时段,则胎死宫内()
A.5~6分钟
B.3~4分钟
C.1~2分钟
D.7~8分钟
E.9~10分钟
参考答案:D
open the windows , please. It's cold outside.[ ]
A. Won't
B. Aren't
C. Don't
D. Doesn't
锅炉炉管爆破时有什么现象?