---How long is it _____ we last met?--- About five years. You haven’t changed much.
You needn’t have ________ the speaker when he was speaking; there was enough time afterwards for you to ask questions.
It’s helpful to put students in a situation _______ they can learn how to cooperate with each other.
Lucy is a very optimistic girl. ______ she is faced with difficulties, she always sees the bright side.
All the people on the list must be told to attend the meeting; you must make sure that no one is _______.
The task is very difficult. I wonder whether we will be able to finish it in the ________ of any other helpers.