will have been对过去情况作肯定推测

问题描述

对过去情况作肯定推测一般是用must have been，但下面的句子中，是用will have been对过去情况作肯定推测：

That will have been Roland. He said he’d be back at 7. 准是罗兰。他说他7点钟回来。

请问它与用must have been对过去情况作肯定推测有何区别？

老师答疑

张老师：

▲这个问题很好，反应了中学英语在情动表过去推测教学方面的不足之处：
will / must have done 都可对过去事件推测，但是 will 的可能性要小，常译为【想必/料是/可能】因此您的例句译文是正确的。
That will have been Roland. He said he’d beback at 7. 准是 / 料是 / 想必是罗兰（到了）。他说他7点钟回来。
He will have spent a long time learning English, beginning when he left school. 他自毕业以来想必 / 料是已经花了很长时间学英语了。
▲还要特别注意千万不可把该结构表将来完成混为一谈。
▲而must have done 意义为【一定】，其可能性最强。
It must have rained last night, for the ground is wet. 昨晚一定下雨了，因为地面还是湿的。
You must have been mad to speak to the servant. 你和仆人说话，一定是发疯了。