The computer plays an important part in our everyday life. It is one of the great __1__ in the world in the __2__ century. It works for us not only at home, in the offices, in big shops, __3__ at schools. Today it is used __4__ many ways. It really __5__ the world large wealth (财富) and happiness.
　　The first computer in the world was __6__ Enid. It was built in America in 1946. It was __7__ and heavy. __8__ it was born, it has been developing very fast. Until now it has gone __9__ four periods（时期，阶段）and changed a lot. There’re many kinds of computers. Computers are getting smaller and smaller and computing faster and faster. It becomes more and more __10__.
　　The computer can do most of the things __11__ the people. It can help us to __12__ about the real world more quickly, to learn __13__ we want to learn and to think __14__ ourselves. __15__ a student in the twenty-first century, you must work hard at it.

　　1. A. inventions     B. discoveries C. robots               D. inventors
　　2. A. twenty-first   B. twenties   C. twelfth      D. twentieth
　　3. A. also             B. but also     C. too            D. either
　　4. A. in              B. to             C. by             D. over
　　5. A. takes            B. helps         C. gets           D. brings
　　6. A. found           B. invented     C. called       D. bought
　　7. A. easy             B. small         C. large         D. light
　　8. A. For              B. Until         C. When      D. Since
　　9. A. by                B. across      C. through     D. against
　　10.A. serious         B. harmful.    C. dangerous D. helpful
　　11.A. for             B. to             C. at              D. with
　　12.A. set              B. tell         C. know               D. talk
　　13.A. what            B. that           C. which        D. who
　　14.A. of               B. about        C. out            D. for
　　15.A. For             B. Be            C. As             D. To