How could you do this to me vs. Why could you do this to me?

[Stupy]

English Grammar Tests, Elementary Level

ESL/EFL Test #174 "Where, Why, What, When and How (1)", question 10

Man: ......... could you do this to me?
Woman: I'm sorry. I have to think about the company and you aren't doing a good job. I have to let you go.

(a) Why
(b) When
(c) Where
(d) How

English Grammar Tests, Elementary Level

ESL/EFL Test #174 "Where, Why, What, When and How (1)", answer 10

Man: How could you do this to me?
Woman: I'm sorry. I have to think about the company and you aren't doing a good job. I have to let you go.

Correct answer: (d) How

Your answer was: incorrect
Man: Why could you do this to me?
Woman: I'm sorry. I have to think about the company and you aren't doing a good job. I have to let you go.
_________________________

what is deferent between why and how

[Mister Micawber]

'How could you...' is idiomatic-- it does not ask for a reason. It means 'I cannot believe that you...'.
_________________
Native English teacher at Mister Micawber's