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Переведите на русский язык следующие предложения:
1. A step-down transformer near the building reduces the high voltage to a safer level.
2. An underground or overhead cable from the transformer leads to the building, where it is connected to a meter that records the energy used by the subscriber.
3. Immediately beyond the meter is a fused main switch to protect the building against an accidental power surge from the grid.
4. The wires are usually copper, although aluminum is also used, and are covered with thermoplastic insulation.
5. The wires must be contained in tubing, which is either metal or plastic.
6. The power densities of dwelling units are fairly low and are declining because of the increased use of fluorescent lighting.
7. Photovoltaic cells, which convert sunlight directly into electricity, in combination with storage batteries can offer these residences a new kind of energy autonomy.
8. Generators also produce the electrical power required for automobiles, aircraft, ships, and trains.
9. The mechanical power may come from a number of sources: hydraulic turbines; wind turbines; steam turbines; gas turbines.
10. The construction and the speed of the generator may vary considerably depending on the characteristics of the mechanical prime mover.
11. Nearly all generators used to supply electric power networks generate alternating current.
12. Since a number of generators are connected into a power network, they must operate at the same frequency for simultaneous generation.
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