【正文】 anting D. be planted 6. Personal puters _____in 1976. It has changed the whole world A. have been invented B. are invented C. were invented D. invented 7. — Do you know who designed the CDROM Around the world in Eight Hours? — Yes. It ______ by Nancy Jackson. A. has designed B. designed C. was designed D. designs 8. The window______ ten minutes ago, and the room is bright now. A. can be cleaned B. is cleaned C. was cleaned D. will be cleaned 9. This kind of food_____ cool, clean and dry according to the instruction. A. should be carried B. must be put C. should be placed D. must be kept 10. — Where did you go last night? — I_____ to go to Li Lei39。t e to join us unless she_______ to. A. tells B. has told C. is told 18. To make our city more beautiful, rubbish_____ into the river. A. can’t throw B. mustn’t be thrown C. needn’t be thrown 19. The persons under 16 years old shouldn’t_____ to go to the Inter bar. A. be allowed B. be allowing C. allow 20