Перепишите. Вставьте попущенные слова. sources origin design steam ancient reliability demand 1. Many traditions are of recent , but some of them date back to times. 2. He is working on the of a new engine. 3. During the Industrial Revolution engines appeared. 4. Many new of energy are used nowadays. 5. We pay much attention to of new devices. 6. The profession of an engineer is always in great .