You will fall behind the others ______ you start to work hard.

Computers are useful machines. They can help people a lot in their everyday life. For example, they can help people save much time, and they can help people work out many problems they can't do easily: Our country asks everyone to learn to use computers except the old people.
Today more and more families own computers. Parents buy computers for their children.
They hope computers can help them improve(提高) their studies in school. Yet many of the children use computers to play games, to watch video or to sing Karaoke instead of studying. So many teachers and parents complain that computers can not help children to study but make them fall behind. So computers are locked by parents in the boxes.
In some other countries, even some scientists hate computers. They say computers let millions of people lost their jobs or bring them a lot of trouble.
Will computers really bring trouble to people or can they bring people happiness? It will be decided by people themselves.
【小题1】Why do we say the computer is a useful machine? Because _______.

Ron loved basketball. One afternoon on his way to a basketball game, he was walking and dreaming about playing college basketball the following year. As Ron was walking to the game, a car hit him so hard that he was thrown three feet into the air.
Ron woke up in a hospital room. When he learned that both his legs were broken, he realized his college basketball dreams were over. Ron did what the doctors told him, but his progress was slow. When he left the hospital, Ron was sent to a health center for physical treatment.
A week after he arrived there, he met Sunny. Sunny was a coach．His legs were hurt  paralysed(瘫痪的) from a skiing accident. Even though he couldn’t move his legs, Sunny coached of a basketball team called the Suns. Everybody on the team played from a wheelchair. Sunny invited Tony to join the game. Tony played badly, but for the first time since the accident, he stopped feeling sorry for himself．
After becoming a part of the Suns, Ron improved quickly. Basketball was like   medicine for him. And whenever Ron became depressed or angry, Sunny was there to encourage and help him. The day before Ron left the center, he had dinner with Sunny. He asked Sunny how he managed to be generous and cheerful, even with his paralysis.
Sunny smiled and said, “It’s really quite easy. When you keep your face to the sun, the shadows(阴影) fall behind.”
【小题1】What happened to Ron on his way to a basketball game?

You will fall behind others _________ you work hard.
A. if                  B. when                C. unless