III. Change the sentences according to the examples.

Example: It is simple to solve this problem. — This problem is simple to solve.

It is difficult to speak to such people. — Such people are difficult to speak to.

1. It is expensive to buy a mink coat.

2. It is impossible to get a good dinner in our canteen.

3. It was difficult to start an engine in such cold weather.

4. It is dangerous to stand on this ladder.

5. It is rather difficult to deal with stubborn people.

6. Here is a simple English book that you can read.

7. The first thing they must do when they arrive is to phone home.

8. This is a problem you should solve by yourself.

9. There is nothing that we can add.

IV. Translate the following sentences and define the infinitive constructions.

1. Lightning proved to be a discharge of electricity.

2. Heat is known to be a form of energy.

3. The student is certain to know that alternating voltage can be increased and decreased.

4. We know the electrons to flow from the negative terminal of the battery to the positive one.

5. This scientist seems to have been working on the problem of splitting the atom.

6. The students saw the thermometer mercury fall to the fixed point.

7. Coal is considered to be a valuable fuel.

8. The electrolytes appear to change greatly when the current passes through them.

V. Define the function of the Infinitive in the following sentences by putting questions to each of them.

1. We have come here to build a new town.

2. I have entered the institute to become a highly qualified engineer.

3. To build a house one must have a plan, necessary materials and manpower.

4. To learn a foreign language it is necessary to read, write and speak every day.

5. To become a good engineer one should know fundamentals of many sciences.

6. To find the state of a mass of a gas, we must know its volume, its pressure and its temperature.

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to electrical substations located near demand centers. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. Transmission lines, when interconnected with each other, become transmission networks. The combined transmission and distribution network is known as the "power grid" in the United States, or just "the grid". In the United Kingdom, the network is known as the "National Grid".

A wide area synchronous grid, also known as an "interconnection" in North America, directly connects a large number of generators delivering AC power with the same relative phase, to a large number of consumers. For example, there are four major interconnections in North America (the Western Interconnection, the Eastern Interconnection, the Quebec Interconnection and the Electric Reliability Council of Texas (ERCOT) grid), and one large grid for most of continental Europe.

Historically, transmission and distribution lines were owned by the same company, but starting in the 1990s, many countries have liberalized the regulation of the electricity market in ways that have led to the separation of the electricity transmission business from the distribution business.