1 - The ability to deal with numbers and mathematical concepts reveals an interesting pattern of differences between girls and boys.

2 - During the period of change young people mature physically, begin to take responsibility for themselves, and start to deal with the world on their own.

3 - New theories may eventually show limitations of the relativity theory and deal with problems that the relativity theory does not cover.

4 - The problem of how to deal with the vast quantities of waste we produce requires our urgent attention.

5 - Employers in the rich world have no choice but to learn how to deal with an ageing workforce, as the baby-boom generation gets older and life expectancies increase.