Lots of rescue workers were working around the clock, supplies to Yushu, Qinghai Province after the earthquake.
| A．sending | B．to send | C．having sent | D．to have sent |
8.Customers are asked to make sure that they ____ the right change before leaving the shop.
| A．will give | B．have been given |
| C．have given | D．will be given |
7.Although the causes of cancer ____， we do not yet have any practical way to prevent it.
| A．are being uncovered | B．have been uncovering |
| C．are uncovering | D．have uncovered |
6.I have to go to work by taxi because my car ____at the garage.
| A．will be repaired | B．is repaired |
| C．is being repaired | D．has been repaired |
5.---Have you handed in your schoolwork yet?
---Yes，I have. I guess it ____ now.
| A．has graded | B．is graded | C．is being graded | D．is grading |
4.It is said that the early European playing-cards ____ for entertainment and education.
| A．were being designed | B．have designed |
| C．have been designed | D．were designed |