I simply couldn't understand how it ______ that you did so m

I simply couldn't understand how it ______ that you did so m I simply couldn't understand how it ________ that you did so I simply could not understand how it came about that you did Actually you don't understand me,so how can I tell you that I can't understand why you all ____ think that I did it. （c） One silly question I simply can’t understand is "How do you I\'m so sorry that i couldn\'t follow through it was so cold that i couldn't feel my The passage is so difficult that he couldn't understand it．W You couldn\'t understand what I said? Tom was ______ that he couldn’t understand ______ difficult The box was so heavy that I couldn't lift it .中为什么用couldn't