-Why does the Lake smell terrible?
-Because large quantities of water .
| A．have polluted | B．is being polluted | C．has been polluted | D．have been polluted |
. Newly-developed materials for spaceships can _________ extreme weather conditions.
| A．hold | B．support | C．stand | D．carry |
Because of global warming, the ice that polar bears depend on for survival _______.
| A．are slowing disappearing | B．is slowly disappearing |
| C．are slowly disappeared | D．have slowly disappeared |
Ten giant pandas are heading to the Shanghai Expo, _________ they will go on year-long display.
| A．which | B．where | C．what | D．when |
-- The terrible accident is under investigation.
-- Actually, quicker action ________ those workers trapped in the mine.
| A．might have saved | B．must have saved |
| C．should have saved | D．could have saved |
A strong earthquake struck Chile's central-south coast on February 22, ________ great damage to buildings
| A．caused | B．to cause | C．causing | D．having caused |