Wolves would starve if food was difficult , especially during the cold winter months.
In modern times, the development of science is ________ .
He insisted that his plan _______ carried out at once.
In order to have a good _______ of English, he decided to go abroad for further education.
A series of books in the library ____ been stolen so that the number of them ____ smaller than before.
It was announced that only when the fire was under control _______ permitted to return to their homes.