Chemical processes _______in the treatment of materials for clothes _______the environment badly in some countries nowadays．
| A．involve；damaging | B．involved；damaged |
| C．involving；damage | D．involved；damage |
All the photographs in this book，__________ stated otherwise, date from the 1950s.
| A．unless | B．until |
| C．once | D．if |
It is believed that if an event is __________，it will surely __________ the readers.
| A．astonished; astonish | B．astonishing; be astonished |
| C．astonishing; astonish | D．astonished; be astonished |
Readers were pleased __________ that a scientist could write about his research in a way __________ ordinary people could understand.
| A．to find; that | B．finding; as |
| C．to find; as | D．finding; that |
-Coach, can I continue with the training?
-Sorry, you can't __________ you haven't recovered from the knee injury.
| A．until | B．before |
| C．as | D．unless |
You can't be careful enough to drive on the __________ road in __________ weather.
| A．freezing; frozen | B．freezing; freezing |
| C．frozen; freezing | D．frozen; frozen |