Passive constructions are made with the auxiliary verb be (or rarely get) followed by an ed-participle. They are often shown in grammar exercises alongside an active construction, as in the following example (you can click on each example to hide or reveal the passive construction): The first sentence is active See the glossary definition and the second passive See the glossary definition . In the active version the subject is "other lines of evidence" and the object is "this conclusion". In the passive version the subject is "this conclusion" and the object is "other lines of evidence" introduced by the preposition "by". The meaning is exactly the same. The only thing which has changed is the emphasis. Usually we use the passive to highlight what was the object in the active construction. What was the subject is now placed in a less prominent position in the by-phrase. In some cases it may omitted (although in this case the sentence would be incomplete without it). A passive sentence which includes the agent is known as a long passive. Where the agent is omitted it is a short passive. Since the verbs on this page all have a subject and are marked for tense, the verbs are all finite See the glossary definition . Passives are also used in a non-finite way and you can see examples of these on the non-finite passive constructions page.
The next example shows that the by-phrase is not always necessary. In the active sentence the subject is "people" but in the passive sentence "by people", the agent See the glossary definition , would sound strange. Who else would use them? And in any case it is too vague. So we can leave it out.
In this example, however, we need to keep the agent. "People's health" is the subject in the passive construction and it is affected by something. We need to know what this is so we need to keep the agent "illegal mining".
In this example we could omit the agent. The passive sentence would be complete without it. However, without it the question remains "How could it be fixed?". So leaving it in gives the answer. Notice that here we don't have a by-phrase but rather a with-phrase.
The examples on this page are all in the present tense. They were all originally written in the active (the first construction in each example). You can consult the original texts here: (Bamber 2020), (Hughes 2021), (Bansah 2022), (Mackey, Lee, and Wee 2021).
As a writer you must decide whether to use an active construction or a passive one. This is not an arbitray choice; there are good reasons for choosing one rather than the other. To see more examples, including the use of other tenses, and reasons why the writer chose a particular construction, see the passive examples page. Passives are also used in a non-finite form. See examples of these on the non-finite passive constructions page. You can also test your understanding of passives on the passives exercise page.