If you had to choose the single most important 1___________(discover) of the 20th century, you would have a real 2_________ on your hands. In just 100 years, the world changed completely. Amazing discoveries were made in medicine, communications and transport, not to 3____________ our knowledge of the world and space. Medical advances 4 ________　 from discovering the causes of diseases under microscopes to surgical procedures 5____________(replace) 6__________(disease) organs with 7________ (donate) ones. Communications changed 8______ the introduction of mobile phones and the way we _9_________(通信) went 10________ writing letters to emailing. We started flying around the world and 11____________(同时), scientists figured 12________ how to 13______(劈开) the atom,　 14________(过去) thought to be the smallest particle of matter 15______　 the universe.

10.He is unable to work _______________ the fall from his horse.

9. What have you been __________________ the conflict?

8.The boss is not satisfied with your work, ______________ , you lose your job.

7. His sister _______________ cancer last year.

6. His speech was very long but few people could _____________ what he meant .

5. ______________ population, China is the largest country in the world.

4. You can __________your computer _________the Internet only after you have paid the service.