School children must be taught how to deal with dangerous ______ .
—What do you think made the girl so glad? —_____a beautiful necklace.
After the meeting, she invited us to dinner at her home and treated us _____ many exotic foods we _____ before. It was really a wonderful treat.
Farmers in China began to use tractors ___ cattle for farming work.
Mr. Wang ____ two boys to send the sick boy to the nearest hospital
—Are you a volunteer now? —No, but I _____. I worked for the City Sports Meeting last year.