I didn't see her in the meeting-room this morning.she(couldn't have spoken) at the meeting

问题描述:

I didn't see her in the meeting-room this morning.she(couldn't have spoken) at the meeting
我觉得应该是:mustn't have spoken

这个句子涉及 虚拟语气
虚拟语气即"她不可能来开会了(但虚拟暗示说她的确来开会了)"
couldn't have done 指"不可能做过某事(但暗示的确那件事情发生了)",这是虚拟语气的固定形式
mustn't因为意思过分绝对,所以一般很少用 一般只用于"禁止"意