With winter _______ on, it's time to buy warm clothes.
You have to wear special clothing, a helmet and a life jacket ____ your raft gets turned upside down or sinks.
I wonder if ____ to come over to my family after work.
As I looked at the memorial, I thought about ____ terrible disaster it was for the people in Nanjing then and ____ they were to fight the Japanese invaders.
Television has many advantages. It keeps us ____ of the ____ news and also provides entertainment in the house.
Susan was expecting her favourite singers, but to her disappointment, ____ appeared.