The teacher is busy ____ correcting papers.
Over the past decades, sea ice in the Arctic as a result of global warming.
—You speak very good French! —Thanks. I __________ French in Sichuan University for four years.
—Why don’t we choose that road to save time? —The bridge to it __________.
The number of foreign students attending Chinese universities ________ rising steadily since1990.
-Why does the Lake smell terrible? -Because large quantities of water .