A strong wind blew off her hat. Convert into passive voice.

Considering that passive voice is all about focusing on the object that is receiving the action and turning it into the subject of the sentence, we would need to identify the parts of the sentence at hand:

Subject: [a strong] wind

Verb: blow off

Object: [her] hat

Then, knowing that active voice is in a certain order (subject + verb + object), now we need to invert that order (object [now subject] + verb [now past participle] + subject [now object ]

Her hat was blown off by a strong wind.

The correct answer would be: Her hat was blown off by a strong wind.

Passive voice is frequently used and it is most often used in formal texts, but it is also used everyday. When we use passive we focus on the object or a person that experiences the action not the one that performs it. Passive voice is formed by using the correct form of the verb to be plus past participle.