Question

英语虚拟语气

Mary couldn’t have received my letter; otherwise she would have replied before now.
这样的句子还有虚拟语气句子么？是平行关系，后面的应是虚拟，前面的是推测其还是虚拟的范畴么？

Answer 1

Answer:前半部分是推测,后半部分是含蓄条件句.
(1)
Could have done 表示“过去本能够做某事却未做(表对过去的虚拟)
Couldn't have done 相当于 can't have done 表“过去不可能做了某事
(其否定形式只表推测,不表虚拟)

(2)含蓄条件句:在特定的上下文或一目了然的情况下，if条件句可以省略，或使用介词短语、副词或非谓语动词等形式来代替if条件句，这种虚拟语气表达形式叫做含蓄条件句。此句中otherwise作副词暗示条件.
"otherwise "相当于 If Mary had received my letter

补充:此句句中逗号应该改成句号或分号,因为"otherwise"作副词只是暗示条件,却不能引导句子.如果用If引导虚拟语气,完整形式如下:
Mary couldn’t have received my letter . If Mary had received my letter, she would have replied before now.

全句译:玛丽不可能收到我的信. 如果她当时收到的话,在这之前她就会回复.

If you still feel confused,leave a message please
祝 学习进步!