So, faced with the Danish advance, Alfred did not risk open battle but harried the enemy.

因此，面对丹麦人的进攻，阿尔弗雷德没有贸然同敌人作战，而是采用骚扰敌人的战术。

and even so, some starting data has to guessed,

既使是这样，有些开始时的资料也不得不依靠推测，

if there is any effect of noise upon mental health it must be so small that present methods of psychiatric diagnosis cannot find it.

如果噪音对精神健康有影响的话，那也一定是微乎其微，以致现代的精神病诊断方法还发现不了。

it is very rarely that one comes across a dead body, except, of course, on the roads.

但是，除非在路上，很少有人遇到这些动物的尸体，

and that this happens at a rate which differs little from person to person,

衰老的速度在人与人之间相差甚微，

and another 700 for the survivors to be reduced by half again.

剩下的一半人再过700年，才会又减少一半。