Easy / Difficult Question

In one interview, the interviewer got impatient about one guy because he could answer all the questions so quickly and arrogantly.

"Tell me your choice," said he to the boy, "I shall either ask you ten easy questions or ONE real difficult. Think well before you make up your mind."

The boy thought for a while and said, "My choice is ONE real difficult question."
I "Well, good luck to you, you have made your own choice!" said the man on the opposite side.

Tell me: What comes first, Day or Night?"

The boy was jolted first but he waited for a while and said: "It's the DAY, sir."

"How??" the interviewer was smiling ("At last, I got you!" he said to himself.)

"Sorry sir, you promised me that you will not ask me a SECOND difficult question!"