• 2021-04-14
    Had electronic computers not been invented, many problems of space flight ______.
  • could not have been solved

    内容

    • 0

      When we arrived at the airport, we were told our flight ______. A: had cancelled B: had been cancelled C: has been cancelled D: cancelled

    • 1

      How many Americans had been killed by AIDS?

    • 2

      It was difficult to ________ how many trees had been destroyed.

    • 3

      How many years had Rip been asleep?

    • 4

      If the personal computer had not been invented, will the information age have arrivied by other means? A: 正确 B: 错误