Exercise 8. Translate the sentences. Pay attention to the functions of the Infinitive.

1. To produce a night all-weather interceptor the designers had to test several types of aircraft.

2. To destroy the ground targets with bombs and missiles is the mission of an attack plane.

3. To fly at low altitudes modern fighters are equipped with radars.

4. The spaceship must develop escape velocity to overcome the gravity of the Earth and to fly to other planets.

5. To improve the aircraft structure without increasing its weight is an extremely difficult task.

6. In order to increase the fighter’s range special equipment for in-flight refueling is used.

7. We can use atomic energy in order to operate an engine.

8. To fly at a high altitude the plane must have special radio equipment.

9. To measure the current is very difficult.

10. In order to melt this metal a higher temperature must be used.

11. To be able to fly was one of the greatest desires of man.

12. To be able to fly people had to know more about nature and its laws.

13. To support the plane in the air requires the development of lift.

14. We use electricity in aircraft to give light, heat and power.

15. To measure the current we must have a special unit.

B.

Be + Infinitive

1. Study these examples:

a) The mission of a fighter is to destroy enemy aircraft. - Задача истребителя состоит (заключается) в том, чтобы уничтожать вражеские самолеты.

Exercise 9. Complete the following sentences by adding the Infinitive to each sentence.

Model: 1. His dream was - to become an officer.

2. What I wanted was - not to be misunderstood.

1. The general idea was -. 2. His hobby is -. 3. The first thing you must do is -. 4. The last thing I meant was -. 5. The main thing is -. 6. The only thing to do was -. 7. Your only chance is -. 8. Your job will be -. 9. My only wish is -. 10. What I want is -.

Exercise 10. Translate the sentences with “ to be + Infinitive”.

1. A very important problem was to find a source of power that could drive the plane forward.

2. One of the tasks which they are to perform is to locate a target.

3. An airfoil is a wing-shaped body, the main function of which is to produce lift.

4. The aim of the research was to discover new sources of energy to supply the power plants.

C.

The Use of the Infinitive without the Particle “ to”

Exercise 11. Translate the sentences. Explain when “to” is not used before the Infinitive.

1. The axial compres­sor engine will give more thrust for the same frontal area.

2. The amount of fuel added to the air will depend upon the temperature rise required.

3. This task must be accomplished with the minimum loss in pressure and with the maximum heat release.

4. The turbine blade tips may rotate at speeds over 1, 500 feet per second.

5. The turbine may consist of several stages.

6. The combustion temperature must not exceed a value that gives a turbine gas entry temperature suitable for the design and materials of the turbine assembly.

7. Thrust can be provided by giving a large mass of air a little extra velocity.