The examiner must have been pleased. He ________pleased.
A. was probably B. should be
为什么答案是A ？ should 表示推测 为什么 B 不对？
Let us suppose that a child suddenly crosses the road. Imagine it ________
A.happening B. will have happened
为什么答案是A ？ Imagine it will have happened 中“it will have happened”从句作imagine的宾语 为什么不对？
參考答案:1.must have been done
表说话人对过去发生的事"推测"..."一定..."
The examiner must have been pleased
检查人士(当时)一定很开心...
表说话人主观的意像...可能examiner (当时)不开心也不一定.
而 should be 是"shall be '的过去时,表"将要,本应该"..
2.happening是 it were /was happening的省略
这题是考虚拟语气...
就如: i wish i were living here
我希望我住在这.(我并不住这,只是我想象的,希望的某种状态)
i suppose you were playing the piano.
而 it will have happened表示的则完全不同/..它是指"注定未来会发生的""未来会被完成的事"
如:the building will have built next year.
这楼明年会被竣工...
it will have happened是现在的某些"迹象"让说话者"肯定"谋事未来一定会发生///
而这句"让我们假设一个小孩子突然过马路",只是一种假设,而非对未来会发生的事的"迹象"或者"依据".