Writing Style

Most sentence patterns that you would have learned use “active voice,” which follows a subject + verb structure. Passive voice refers to a sentence pattern where the object, not the subject, is placed at the beginning of the sentence. 

Watch this introductory lesson or this extended lesson on passive vs. active voice in our LC elearning modules class in D2L.

Active and Passive Voice Compared
Active Voice: The nurse administered the medication to the patient.
Passive Voice: The medication was administered to the patient.

Active voice is preferred in APA style, but passive voice is acceptable when you want to focus on the object that receives the action, not the agent that carries out the action. In the first example above (Active voice), the focus is on the nurse. In the second example, the focus is on the medication. 

Passive Verb Structure
Use the verb “be” as a helper with the past participle form of your verb.
Present tense passive verb:  Medications are administered by nurses.
Past tense passive verb: The patient was assessed before being admitted.

Further Information
"Active Versus Passive Voice," Purdue University OWL 
"Active and Passive Verb Forms," Englishpage.com (with multiple forms of the passive)