---Who is the tallest boy? ---It ______ be John.. John is of medium height.
—What does our new maths teacher Nancy like?—______
Zhang Ming has learned English for two years, but he can ______ understand native speakers.
Look at the ______ girl! How ______ she is singing.
—______ your sister ______ in Greener China for a long time?—Yes.She joined it five years ago.
If you keep ______ ,you’ll be a very good swimmer one day.