What is a population pyramid

Occurrences of major earthquakes are considered unusual, but minor tremors happen frequently. which word is an adjective?

Which three parts of these excerpts reflect the idea that war affects not only the minds of the combatants but also their physical reactions?

Which resource might provide a student who is just starting a research project with a list of credible sources of information to consult? o a. a biography of an early computer scientist o b. an article on new developments in computing o c. a book about programming languages o d. an online encyclopedia article or wiki