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Bài 1 :Put the verbs in brackets in the past simple tense os past perfect tense
1. Neil Armstrong and Buzz Aldrin (collect)......had collected.............. some moon dust samples before they (return)....returned......... to Earth.
2. By the time Yang Liwei (become)........became......... the first person sent into space by the Chinese space program in 2003, NASA had already (send)........sent............ over 100 people.
3. After the spaceship Soyuz 37 (be).......had been...... in orbit around the earth, Pham Tuan and Viktor Gorbatko (conduct)........conducted...........some experiments.
4. When we (arrive)...............arrived...... in Kennedy Space Center, the space shuttle had already (launch)....been launched............. into space.
5. Dennis Tito had already (complete).......completed........ 900 hours of training by the time he (fly).........flew......into space in 2001.
Điền từ vào ô trống
Manned space-craft travel at speeds of almost five miles a second. But space-craft are slow..compared...with the fastest traveler in the ..known...universe-light. Scientists calculate that light travels 186000 miles a second!
Swift ....as..it is, light takes time to cross interstellar space. Light from Sirius, a neighboring star, travels for nine years to...reach...us.
Because of the time lights takes to travel the....distance....of space, it is possible to "see" an event long.....after...is has happened. In AD 1054, Chinese astronauts recorded the..appearance.... of an object that ..lit.. up the night sky. They were seeing an exploding star. Yet scientists today calculate that the stars ...exploded..... more than four thousand years ago. .....Like.... the Chinese observers, we too may "see" happening vast distances away and long before our own time.
Điền từ vào ô trống
Manned space-craft travel at speeds of almost five miles a second. But space-craft are slow..compared...with the fastest traveler in the ...observable..universe-light. Scientists calculate that light travels 186000 miles a second!
Swift ...as...it is, light takes time to cross interstellar space. Light from Sirius, a neighboring star, travels for nine years to...reach...us.
Because of the time lights takes to travel the....distance....of space, it is possible to "see" an event long.....after...is has happened. In AD 1054, Chinese astronauts recorded the...appearance... of an object that ..lit.. up the night sky. They were seeing an exploding star. Yet scientists today calculate that the stars ...exploded..... more than four thousand years ago. ....Like.... the Chinese observers, we too may "see" happening vast distances away and long before our own time.