Infinitive

Variant III

1. A sanitary engineer protects the quality of water by treating and purifying this water to be used for domestic purposes.

2. The plumber lays the pipes to carry clean water into the house and to carry waste water away to the sewers.

3. In construction of a house the first step is to examine the soil in order to find its bearing power.

4. To transport water for populated districts the builders also construct aqueducts.

5. Green plants are considered to be very important because they clean the air, reduce contamination and so improve living conditions.

6. The internal combustion engine is known to cause more pollution than the factories.

7. The building regulations require external walls to be adequate to prevent heat loss from the building.

8. Many people consider the motor cars to be the main source of air pollution.

9. Concrete has a low tensile strength and needs to be reinforced with steel to form a structural member.

10. In order to understand what civil engineering is you must consider the development of different branches of engineering.

Infinitive

Variant IV

1. The aggregates are graded in size from fine to coarse in order to reduce the amount of void space to be filled by cement.

2. Elements to be employed for heat-insulation undergo supplementary treatment.

3. Before calculating the required sizes of beams or columns it is necessary first to determine the loads carried by the structure.

4. To make a house quite a lot of people all work together.

5. Cement is known to be the most important component of concrete.

6. When the water is added to the cement, this causes the whole mixture to set and hardening, forming a solid mass.

7. Water-reducing admixtures are found to facilitate placing of concrete under difficult conditions.

8. If alumina is not correctly proportioned it will cause the bricks to crack when being burnt.

9. Excessive amounts of air-entrainment are found to reduce the strength of concrete.

V-ing FORMS

Variant I

1. Besides having a low strength due to a high water-cement ratio concrete has even a lower strength because of poor compaction.

2. Having rather small strength, aluminum cannot be used for building structures.

3. Concrete is made by binding together particle of sand and gravel, stone or broken brick.

4. When choosing the building materials a building engineer must consider the conditions under which the chosen material is to operate in a built structure.

5. The value of this property is apparent in forming composite structures, laminate and the like.

6. The tower cranes are employed for lifting building materials onto the building being erected.

7. Cement is a binding material which hardens on drying and is used with a suitable aggregate to form a concrete.

8. Bricks serve only as a load-bearing material.

9. Being cured under pressure in autoclaves, concrete attains its great strength in 4 or 6 hours.

10. Suitable concrete aggregates may differ widely in their properties, the differences being as great as those between various cements.

V-ing Forms