Charles Babbage is generally considered ________ the first computer.
| A．to invent | B．inventing | C．to have invented | D．having invented |
There is only one of the oldest customs that ________ in this district up to now.
| A．was kept | B．were kept |
| C．has been kept | D．have been kept |
Modern teaching equipment as well as tens of computers _______ to the village school last week.
| A．were sent | B．was sent |
| C．has sent | D．had been sent |
The number of air crashes that _______ in developing countries _________ increasing.
| A．happens; is | B．happen; is |
| C．happens; are | D．happen; are |
Bill suggested ________ a meeting on what to do for the Shanghai Expo during the vacation.
| A．having held | B．to hold |
| C．holding | D．hold |
_________many times, he finally understood it.
| A．Told | B．Telling |
| C．Having been told | D．Having told |