The passive voice is more common in formal written English. It is often used in newspapers, academic and scientific writing and reports, which try to be less personal. Most passive sentences do not have an agent, as the focus of the sentence is not on the doer of the action but on its recipient. As a rule, the agent is only mentioned in the passive sentence if it is important new information which cannot be omitted:
DESCRIPTION OF A PROCESS AND WRITING A REPORT
We often use the passive voice in describing processes and writing reports, when the emphasis is on the actions and not on the people who perform them. The agent is usually omitted:
EXAMPLE:(identify the use of passive voice.)
How does a Pressure Cooker work?
Water is poured into the pressure cooker and the food to be cooked is placed in it. The pressure cooker is then placed over the flame of a stove and the water begins to heat. When the boiling point, about 100 degrees centigrade, is reached, steam begins to form. However, the steam is not allowed to escape and pressure builds up within the cooker. As the pressure increases, the temperature within also increases and food is cooked. To prevent explosion due to high pressure, the cooker has a weight and a safety valve that let out excess of steam.