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，

First the electroencephalograph (which is simply a device for recording the electrical activity of the brain by attaching electrodes to the scalp) shows that while there is a change in the pattern of activity during sleep,

第一点，脑电图记录仪（不过是一种把电极接到头皮上记录脑电活动的仪器）显示，人在睡眠时大脑活动的方式有变化，

Then the sound of rumbling thunder reached the watchers on the shore, as cargo, ballast,

岸上的观众听到船上发出了雷鸣般的轰响。当物品、压舱物、

Education, with its cycles of instruction so carefully worked out,

教育，以其教学周期如此精心地安排，

But these are not analogous to what happens when man ages.

不过，这些衰老的情况同人并不相似。