________ caused the accident is still a complete mystery.
Car seatbelts save lives. Every driver should wear________to ensure their safety.
Last week a tennis ball hit me on the head, but I tried to _______ the pain, believing that it would go away sooner or later.
Many people tried to leave the country,________there was much violence and a serious shortage of food supply.
After________careful consideration,they finally decided that each child will be offered________university education.
You are working too hard. You'd better keep a ________ between work and relaxation.