FOCUS on GRAMMAR:

The Passive Voice:

The passive voice is less usual than the active voice. The active voice is the "normal" voice. But sometimes we need the passive voice.


In an active sentence, the person or thing responsible for the action in the sentence comes first.
In a passive sentence, the person or thing acted on comes first, and the actor can be added at the end, introduced with the preposition "by." The event or the action is more important than the actor or agent.

When do I use passive voice?

• When the actor is unknown:
The cave paintings of Lascaux were made in the Upper Old Stone Age. [We don't know who made them.]


• When the actor is irrelevant:
An experimental solar power plant will be built in the Australian desert. [We are not interested in who is building it.]


• When the actor is a generalized actor or agent
Bicycles are widely used in the city instead of public transport. (people in general )


• When the actor is obvious
Linda has been arrested (we assume by the police)


• When you want to be vague/veɪg/ or impersonal about who is responsible for an action:
Lots of mistakes were made. 
It has been decided to reduce all salaries by 10%.


• When you are talking about a general truth:
Rules are made to be broken. [By whomever, whenever.]


• When you want to emphasize the person or thing acted on. 
Insulin was first discovered in 1921 by researchers at the University of Toronto. It is still the only treatment available for diabetes.


• When you are writing in a scientific genre: lab reports and scientific research papers.
The sodium hydroxide was dissolved in water. This solution was then titrated with hydrochloric acid.*


*In this sentence you can count on your reader to know that you are the one who did the dissolving and the titrating. The passive voice places the emphasis on your experiment rather than on you.