Complex sentence: Prince Alexander was born in London, United Kingdom, to the Duke and Duchess of Teck, and was educated at Eton College before moving on to the Royal Military College, Sandhurst, for training as an officer.
Split into simpler sentences: Prince Alexander was born in London, United Kingdom, to the Duke and Duchess of Teck. His elder sister Princess Mary, later became Queen consort of King George V. He was educated at Eton College before moving on to the Royal Military College, Sandhurst, for training as an officer.