With Halloween approaching, there exists a real concern among parents and teachers __________ trick or treating will become a seriously anti-social activity.

We’ll go for a walk if it ___  __ tomorrow.

Suddenly the idea came to me       I might turn to Mr. Smith for help.

 My grandmother has kept the photo ______ she can see it every day for a couple of decades. 

 It was the training _____ he had as a young man _____ made him such a good engineer.