E-mail, as well as telephones, ___ an important part in daily communication.
| A．have played | B．is playing | C．are playing | D．play |
76. All flights _______ called off because of the terrible weather, they had to go there by train.
| A．were | B．had been | C．being | D．having been |
77. --- Have all the important letters been delivered at the first time?
--- I’m sorry. _______ only 40% of them.
| A．It is | B．They are | C．There are | D．It has been |
78. --- You _____ repay this debt this week according to the agreement.
--- Don’t worry. I _______ pay it off before the deadline.
| A．must; will | B．shall; must |
| C．should; am due to | D．shall; am bound to |
79. Ming and Qing tombs have ______ relatively undamaged. They, ______, have suffered some damage from centuries of exposure, wars and deliberate destruction.
| A．left; nevertheless | B．been remained; however |
| C．survived; though | D．excited; yet |
80. _______ the right decision _____ the future is probably the most important thing we will ever do in our life.
| A．Making; concerned | B．Make; concerning |
| C．To make; concerned | D．Making; concerning |