声环境评价等级为一级，噪声源噪声级数据获得的途径必须采用( )。 A．类比分析法

No decision ______ about the trip until the headmaster comes back. [ ]

A. is made

B. will be made

C. is being made

D. has been made

外伤性颅内血肿的致命因素是（）。

A.急性脑受压→脑疝

B.一侧瞳孔散大，对光反射消失

C.弥漫性脑水肿

D.蛛网膜下腔出血

E.昏迷→肺部感染

足月妊娠时，羊水无回声区最大前后径为（）

A.10cm

B.2cm

C.4cm

D.5cm

E.6cm