11.  A can of whipped cream uses nitrous oxide, an anesthetic, as a propellant.

12.  A careful note should be made against any sub-contractor used by the builder who subsequently proved to be unsatisfactory.

13.  A case-study can be carried out, using almost any method of research, though the less statistical methods are usual.

14.  A catalyst facilitates a chemical process without being used up or changed itself.

15.  A chauffeuring service is offered using a dashing S-type Jaguar.

16.  A chemical sprout inhibitor should be used for long term storage.

17.  A clip-on bobbin with a Betalight is used at night, with the Optonic of course.

18.  A Colgate Marketer demonstrates how to use the toothpaste and a toothbrush.

19.  A colour changer will appeal to anyone who likes to use a lot of colour or different yarn textures when pattern knitting.

20.  A combination of psychometric methods and direct observation and discussion was used.