When travelling in buses or trains, we are likely to have conversations _____ we give information or opinions about different things.
Tony was very unhappy for _______ to the party.
The research is so designed that once _______ nothing can be done to change it.
After graduation she reached a point in her career __________ she had to decide what to do.
Edward, you play so well. But I ________ you played the piano.
Not until I began to work ________ how much time I had wasted.