A friend of mine was travelling in the train and opposite him sat a gentleman reading The Times. Every now and then he took a complete sheet of the newspaper, crumpled it up, opened the window, threw it out and shut the window. After he had done this two or three times my friend said: "Excuse me, sir, but I am most interested in what you are doing. May I ask why you do it?"

"Oh yes", he replied, "it keeps the elephants away."

"But", my friend said, "there aren't any elephants here." "Of course not," came the answer. "That proves it works!"

Na frase: May I ask why you do it?" Qual verbo teria o mesmo significado?

a) Should
b) Ought to
c) need
d) can
e) must​