— It was a heavy snow last night. Are we all here now?

— Yes, and _____ of us was late for school.

A．all

B．either

C．neither

D．none

在狭窄骨盆中发生胎儿窘迫的主要原因是：

A．手术助产机会大

B．胎儿宫内感染

C．胎儿慢性缺氧

D．胎膜早破，脐带脱垂

E．产程延长，胎头受压