Re: "Passive" sentence structure
Here's an example I found on the internet that might help clear things up regarding agent:
Originally Posted by ESL-lover
How do we know we know if a sentence is using the passive voice?
The horse was seen by Carolyn.
The subject: the horse
The action: seeing
The acting agent (who acts?): Carolyn
The subject and the acting agent are not the same. Therefore, this sentence is in passive voice.