Twenty-five percent of the water in this river _____ dirty in the past.A. is B are C. was D. were
When the star fell ____ the darkness quickly at night,all the people felt it amazing.
It's an either-or situation.You can watch TV or play games,but you can't do ____.
--I'd like to book a room for tonight.--Sorry,sir,but we don't have any rooms ____ right now.
The astronauts were so interested in____ beauty of nature that they took lots of pictures in____ space.
He speaks ________ fast ________ I can’t follow him.