We must do something to _____ factories _____waste water into the river before it is cleaned.
When you talk about a person's _____, you are referring to the country, race, or social class of their parents or ancestors.
Do you think _____ possible to work out a correct figure of the income that the Expo will bring to China?
—You’ve finally figured out the puzzle! —Yeah, in a complex way, _____.
—I’m terribly sorry, Lucy.I’ve left your notebook at home. —_____? I reminded you last night.
_____ we have finished the course, we shall start doing more revision work.