The microphone enabled them to keep in touch, in other words, it made it _____ for them to contact each other.
Beijing, the capital of China, is one of ______ cities in the world.
— Whose notebook is this? — It could be ______.She studies French.
Your ability has never been in doubt-- the question is ____ you are prepared to work hard.
At last we came to a mountain, at the top of which ______,
---Must I take this medicine, Mom? It ________ so terrible.---Yes, you must take it for another three days.