Прочитайте текст
Christopher Columbus was born in the seaport town of Genoa in Italy, about the year 1451. He was only 14 years old when he first sailed to the East. His life on the sea, talks with sailors and the results of science made him sure that the earth is round. He wanted to reach India by a westward voyage. He also wanted to discover a new and shorter way to the East.
Columbus set sail with his crew on the 3rd of August, 1492. He was on the ocean for ten weeks. After many hardships he and his sailors saw land. The land was America.
Columbus continued his explorations but he always thought that the islands he had sailed to were the West Indies and he died never knowing that he had discovered a new continent.
Закончите предложение в соответствии с содержанием текста
Columbus was sure that _____.