---Do you know ____________ the population of China is?---Yes, it has the __________ population in the world, about 1.3 billion.
—Do you know ____ in America? —Sure. It's the third Sunday of June.(2014,云南)
—I don't know ____ or not. —Neither do I.You may ask his teacher.
I didn't know ____.
—What did your father say? —He asked us ____.
—Could you tell me ____? —Sure. Walk straight along this street and you'll find it.