Reportedly, yesterday a group of American soldiers were walking along the road in Iraq when a bomb was _______, three of whom were killed.

A．set off

B．set out

C．set up

D．set about

E-RAB异常释放的原因有（）

A.网络拥塞

B.无线层/传输层问题

C.UE长时间处于不活动状态

D.核心网问题

E.切换失败