"To be" and its functions. "To have" and its functions

V. Translate the sentences paying attention to the verbs in Subjunctive Mood:
A. 1. It is necessary that the aircraft engine should combine efficiency and
lightness.

2. 
   It is highly desirable that physicists should solve the problem of control of dangerous radiations before we can widely use atomic energy.
   
3. 
   It is essential in the application of the turbojet engine to the propulsion of
   missiles that the thrust per unit of frontal area be as large as possible.
   
4. 
   It is important that the propellant remain liquid at the lowest temperature.
   
5. 
   It is necessary that an aircraft engine function properly at a wide range of speeds, atmospheric conditions and altitudes.
   
6. 
   To maintain an aircraft hydraulic system in good order it is essential that a means of operation on the ground be provided.
   
7. 
   It is highly desirable that a person operating an aircraft have a good knowledge
   of the functions of engine controls and instruments.
   

B. 1. It is required that all research instruments be light and compact.

2. 
   Much of to-day's scientific research requires the solving of difficult mathematical problems, some of which would require year to solve by the usual methods.
   
3. 
   We wish Tsiolkovsky's ideas were put into practice.
   
4. 
   The demand is that all measurements should be made very accurately.
   
5. 
   The fundamental principle of generator action requires that lines of force be
   cut by wires.
   
6. 
   He suggested that the experiment with liquid fuel rockets should be continued.
   

C. 1. If there were no friction we could not even walk.

2. 
   The Earth behaves as if it were a large magnet
   
3. 
   Our understanding of the nature of airflow would be much easier if the flow could be seen.
   
4. 
   If there were no frictional losses in a machine, we could get as much work out of it as we put into it.
   
5. 
   It would be much easier to compute satellite orbits if the Earth were perfectly spherical and had no atmosphere.
   
6. 
   If one burnt 1 Ib of fuel and all the heat produced were used in heating water, it would be possible to increase the temperature of about 8 ¹/₂ tons of water by 1° Fahrenheit.
   
7. 
   If the Earth's axis were perpendicular to the plane of its orbit, all parts of the world would have about 12 hours of daylight and 12 hours of darkness every day of the year.
   
8. 
   If one could gather all the parts of an exploding atom, their total weight would be slightly less than the weight of the original atom.
   
9. 
   In many cases air way be treated as if it were an ideal fluid.