There was a large box behind the door and Peter couldn't _____ falling over it in the darkness.
76. All flights _______ called off because of the terrible weather, they had to go there by train.
77. --- Have all the important letters been delivered at the first time? --- I’m sorry. _______ only 40% of them.
78. --- You _____ repay this debt this week according to the agreement. --- Don’t worry. I _______ pay it off before the deadline.
79. Ming and Qing tombs have ______ relatively undamaged. They, ______, have suffered some damage from centuries of exposure, wars and deliberate destruction.
80. _______ the right decision _____ the future is probably the most important thing we will ever do in our life.