-- _____is that used for?---_____ the floor.
--- Where will you start your work after graduation? --- Mmm, it’s not been decided yet.I _______ continue my study for a higher degree.
Many clothing manufacturers now substitute artificial silk _____ natural silk to cut down costs of production.
--- Where are you, Nancy? --- Here in the sitting room, _______ to Professor Smith.
Canada is a country ______ many different nationalities as well as one with foreign immigrants ______ the majority of its population.
--- Mum, I’ve at last passed the final exam.--- ________