Against these figures, it was found that only 5% of women snore regularly, while the rest are constantly woken or kept awake by their trumpeting partners.(与这些数字相比,只有5% 的女性经常打鼾;而其余则经常被与她们同睡、像吹号似地打着呼噜的男人吵醒或弄得睡不着。)——《新概念英语》
这里的“are constantly woken”是一般现在时被动语态,而“kept awake”则是过去时的系表结构。我觉得这句话就是在叙述一般的状态,为什么要用过去时“kept”?