11.   A considerable number of students left after the first year.

12.   A considerable number of voters changed their minds at the last minute.

13.   A definitive list of words was derived from a number of machine-readable dictionaries.

14.   A disturbing number of babies are abandoned by their mothers.

15.   A fair number of final bids which came in under the reserve price were later accepted.

16.   A falling birth-rate is brought about by a large number of changes in society.

17.   A final factor that affects the number of children desired by developing world couples is infant mortality.

18.   A fixed number of tickets will be on sale the day of the show.

19.   A general concept can be exemplified by any number of particular instances which need not stand in any causal relation with each other.

20.   A great number of emigres arrived daily from the mainland, left homeless and often destitute of all worldly possessions.