The victim ________ (本来会有机会活下来) if he had been taken to hosp

1.这种虚拟语气的句子按道理是应该配套用的：主句had done +从句would have done.但是有些情况下可以用混合型,也就是不完全配套.本句中答案用would have a chance to survive是表示与现在事实相反,也就是说 那他“现在”还可能活着.想一想如果改用would have had a chance的话,就表示与过去事实相反,也就是说那他“当时”就有机会活着——这肯定不是说话者的本意.
2.could have done也表示虚拟语气,它的含义是“本来能做但没有做”,如He could have passed the exam.(本来能考及格但是没有）.本句它和would have done的意思和用法差不多,也不好用.

The victim ________ (本来会有机会活下来) if he had been taken to hospital in time.
此句我认为不是虚拟语气。是真实条件句。因为if he had been taken to hospital in time.
动作在先。主句动作在后。

would have done 是因为would have 后面是一个动词，而该题的意思是有机会活下来，强调的是机会这个名词，所以它后面直接是would have a chance to survive 。
如果题目的意思改为“本来会活下来”就可以说成是would have survived.
个人意见，仅供参考哦

动词的语气——虚拟语气(The Subjunctive Mood)
一、语气的定义和种类
l、语气：语气是动词的一种形式，它表示说话人对某一行为或事情的看法和态度。
2、语气的种类：
(1)陈述语气: 表示动作或状态是现实的、确定的或符合事实的，用于陈述句、疑问句和某些感叹句。如：We are not ready. 我们没准备好。What a fine da...

理论上是would have done 这种情况是接一个动词，而你接了一个名词