Hurry up! The plane is _______ in fifteen minutes.A thinking of B waiting for C taking off D walking up
—What class are they having? —Math. Their math teacher is _____ the classroom.
—What does your sister usually do in the evening? —She usually______ TV, but now she _____ a book. .
—How does your father go to work? —He often goes to work __________.
After a long hiking, the boy was ________ tired to walk.
— There are still many old city walls in Xi’an, _______? —Yes, there are.