The volunteers for the Shanghai World Expo are busy from dawn ______ dust but they feel very proud of it.
| A．at | B．on | C．till | D．in |
Playing on the football pitch ____________________.
| A．some students are with their P.E. teacher |
| B．their P. E. teacher is with some students |
| C．some students with their P. E. teacher are |
| D．are some students with their P. E. teacher |
__________ that these creatures are linked to a common ancestor.
| A．As is believed | B．What is believed |
| C．That is believed | D．It is believed |
These viruses, if ________ in, can result in illness or even death.
| A．breathing | B．breathed | C．breathe | D．to breathe |
Please take down my telephone number ________ something important happens.
| A．in case | B．now that | C．even though | D．as if |
Mountain climbing ________ be very tiring, and many people feel sick ________ the atmosphere gets thinner.
| A．may; while | B．can; as | C．must; though | D．should; for |