1) The word "guitar" contains three vowels: U, A, and I.

2) The word "computer" contains three vowels: O, U, and E.

3) International relations encompass the study of relationships between nations, including diplomacy, treaties, and foreign policy. It examines the interactions and dynamics among different countries in the global arena.

4) The ancient Egyptian civilization, with its impressive pyramids, pharaohs, and hieroglyphics, flourished along the Nile River for thousands of years.