he must have an accident,or he ()here then.应该填什么?

he must have an accident,or he ()here then.应该填什么?
he must have an accident,or he ()here then.应该填什么?

he must have an accident,or he ()here then.应该填什么?
had been
or 是虚拟语气的提示词
must have done 是对过去的肯定推测,表明是过去式
虚拟语气的时态是退后一个时态,那么原来的过去式,在虚拟语气中,就变成过去完成时,had been