When we want to describe a process, we aren’t usually interested in the people doing each thing in the process. We therefore normally use the passive voice (strona bierna). We are also describing a process which is always true, so we use the present simple.
In the passive voice, the subject of the active verb (strona czynna) is removed and the object of the active verb becomes the new subject of the passive verb.
Górnicy wydobywają surowce. (surowce is the object)
Miners extract raw materials.
Surowce są wydobywane. (surowce is now the subject)
Raw materials are extracted.
In Polish, there are two forms that you use for the passive voice;
być + imiesłów przymiotnikowy bierny (niedokonany)
zostać + imiesłów przymiotnikowy bierny (dokonany)
In English, there is only one form and we don’t have a special form of the verb, we simply us the past participle (3rd form of the verb).
be + past participle
When we use the passive, we are usually talking about non-living things and we therefore normally only need to use two forms of the verb be:
is – for singular and uncountable nouns
are – for plural nouns.
Surowiec jest wydobywany.
The raw material is extracted. (singular noun)
Surowce są wydobywane.
Raw materials are extracted. (plural noun)
Remember that for regular verbs, like extract (wydobywać), the past participle is the same as the past form. You only have to add –ed to the main verb.
extract – extracted