1 - For nearly two decades technical and financial assistance to Third World population and family planning programs has been an important component of foreign aid programs.

2 - Nicotine is only a small component of cigarette smoke, which contains more than 4,700 chemical compounds, including 43 cancer-causing substances.

3 - The causes of schizophrenia are unknown, although the disease has a strong genetic component.

4 - There air two main things that make aircraft engineering difficult: the need to make every component as reliable as possible and the need to build everything as light as possible.

5 - There is a considerable body of research showing that eye contact is a key component of social interaction.