1) The English alphabet has five vowels: A, E, I, O, and U.

2) The first computer mouse was invented by Douglas Engelbart in 1964 and consisted of a wooden shell and two metal wheels.

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 word "umbrella" contains three vowels: U, E, and A.