The most frightening words in the English language are, "Our computer is down. " You hear it more and more when you are on business. The other day I was at the airport waiting for a ticket to Washington and the girl in the ticket office said, "I’m sorry, I can’t sell you a ticket. Our computer is down. "

"If your computer is down, just write me out a ticket. "

"I can’t write you out a ticket. The computer is the only one allowed to do so. "

I looked down on the computer and every passenger was just standing there drinking coffee and staring at the black screen. Then I asked her, "What do all you people do"

"We give the computer the information about your trip, and then it tells us whether you can fly with us or not. "

"So when it goes down, you go down with it. "

"That’s good, sir. "

"How long will the computer be down" I wanted to know.

"I have no idea. Sometimes it’s down for 10 minutes, sometimes for two hours. There’s no way we can find out without asking the computer, and since it’s down it won’t answer us. "

After the girl told me they had no backup computer, I said. "Let’s forget the computer. What about your planes They’re still flying, aren’t they"

"I couldn’t tell without asking the computer. "

"Maybe I could just go to the gate and ask the pilot if he’s flying to Washington, " I suggested.

"I wouldn’t know what gate to send you to. Even if the pilot was going to Washington, he couldn’t take you if you didn’t have a ticket. "

"Is there any other airline flying to Washington within the next few hours"

"I wouldn’t know, " she said, pointing at the dark screen. "Only ’IT’ knows. ’It’ can’t tell me. "

By this time there were quite a few people standing in lines. The word soon spread to other travelers that the computer was down. Some people went white, some people started to cry and still others kicked their luggage.

Why do you think they had not a backup computer（）

A. Because it was easy down.

B. Because it was very expensive.

C. Because it was not advanced enough.

D. Because it was not as big as the main computer.