41.   It would work by using genetically-engineered parts of the HIV virus to inject healthy people.

42.   The therapy works by increasing the healing and life energy within the body, bringing about better health.

43.   It works by boosting the supply of serotonin a chemical produced naturally in the brain.

44.   It works by scanning electric pulses in the brain which form five types of waves each representing a different sound.

45.   The third works by making cancer cells susceptible to laser light which can be used to destroy them.

46.   Since such changes are inherently unquantifiable, it is impossible to say whether or not people were generally working harder by the end of the boom.

47.   It works by identifying the key skill gaps and providing a structured approach to the delivery of the training.

48.   There are three types, called cationic, anionic or nonionic depending on whether they work by carrying a positive, negative or zero electric charge respectively.

49.   It works by having a drawer full of such things as syrup, yoghurt and mustard, and tunnels reaching the drawer, simulating the real ant hills.

50.   There are some horses who are really just avoiding working by shying at everything.