However busy we are, we need to take exercise. Not only___________us keep healthy, it also stops us getting fat.
| A．it helps | B．helps it | C．it does help | D．does it help |
Mary went to the box office at lunch time, but all the tickets __________ out.
| A．would sell |
| B．had sold |
| C．have sold |
| D．was selling |
It took me a long time before I was able to fully appreciate what they __________ for me.
| A．had done |
| B．did |
| C．would do |
| D．were doing |
—Were you surprised by the ending of the film?
—No. I __________ the book, so I already knew the story.
| A．was reading |
| B．had read |
| C．am reading |
| D．have read |
Tom was about to close the window __________ his attention was caught by a bird.
| A．when |
| B．if |
| C．and |
| D．till |
Mary made coffee __________ her guests were finishing their meal.
| A．so that |
| B．although |
| C．while |
| D．as if |