Перепишите и переведите предложения, обращая внимание на употребление Participle II . Подчеркните причастия II в английских предложениях и в переводе.
1. There are many current systems adopted on the world-electrified railroads.
2. For very high potentials used on long distance transmission lines extra precautions as to insulation are required.
3. The advantage of the a.c. system lies in the high efficiency obtained.