If ____unsolved, the problem of food safety may lead to more serious results.

.The detective, ______to read a newspaper, glanced at the man ______next to a woman.

When           to a certain temperature,water can be turned into steam.

Mr Jackson was very angry to find the car he had had _____ yesterday broke down again.

Now that you’re grown up，you’d better spend your time just on the things you find_______.