There were many people standing by, but _____ of them were willing to help the poor boy.
Mr Li would like to _________ us an interesting story.
It was not until he came back _____ he knew the police were looking for him.
Was _____ that I saw last night at the concert?
It is _____ my father worked _____ I work now.
It is the protection for the trees _______ really matters, rather than how many trees are planted.