—What do you think of being a volunteer, John?—I find it a stressful job but one ___ you can really help people.
---What’s wrong with my stomach? ---There is nothing serious; you can __________.
It was the training _____ he had as a young man _____ made him such a good engineer.
It was not until he came back _____ he knew the police were looking for him.
I hate _____ when the light turns red and the people don’t move until it is about to turn green again.
______ today, he would get to Germany by Friday.