--- Tom, where is your father? --- I’m not sure. He_______ in his office.
—How often do I need to feed the dog? —It ________ food every day, or it will be hungry.
—It's difficult to get to the other side of the river. —I think a bridge ________ over the river.
Flowers_____ along the road last year.
.Pens are used for on paper.
— Do you know in ancient China? — I have no idea. But I know people once used tree leaves to make paper.