Can you find her purse? If she's gone somewhere she will have taken it. [《高中英语教科书》第三册(上),人教社,p.55]
与该书配套的《教师教学用书》(p.148)对上面的句子做了如下注释：
“句中的主句用的是将来完成时态,其构成是‘will + have + 过去分词’,它表示在将来某个时候已完成的动作。不过此句中的 will 用作情态动词,意思是‘一定会’。例如:When they arrive tomorrow afternoon, I will have already left. 他们明天下午到达时,我将已经离开了。
We will have done the job two days ahead of time if it doesn't rain. 如果不下雨,我们定能提前两天完成这项工作。
We will have completed the railway by the end of next year. 我们将于明年年底以前建成这条铁路。”
我认为[问]中的 will have taken 与将来时间毫无关系,怎么能说它是“将来完成时态”呢?
该书说 will have taken 是将来完成时态, 是不正确的。该书所举的三个例句都是讲动词将来完成时用法的, 与课文中的句子完全对不上号。
应当特别注意,该书所举的例句中的 will have done 与[问]中的 will have done 虽然形式相同,但在结构上却有本质的区别。前者是助动词 will + have done 构成将来完成时,而后者则是情态动词 will + have done,表示现在对过去发生的事件的推测(讲的是目前的推测),其用法相当于 must(may, might) + have done。但是,这里的 will 不能译为“一定会”,而应译为“可能”“想必”“会”,因为 will 所表达的说话人对推测的肯定程度或把握程度比 must 要小。
They'll have got home by now, won't they? 这个时候想必他们已经到家了,是不是?请与 must(may, might) have done 作一对比(都表示对过去发生的事件的推测):
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In actual fact, I think you're right. And I can't find her passport anywhere. So she must have taken that too. 事实上，我认为你是对的。而且我哪里都找不到她的护照。所以她一定也带走了。
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Something may have happened to her. She might have had an accident. 也许她发生了什
么事情,或许出了意外事故。
[句意]你能找到她的钱包吗？如果她去了什么地方，她会带上钱包的。