ABSTRACT
A passive construction is one in which the subject of the sentence experiences the action of the verb rather than being the originator of that action. Compare these two sentences:
The dog chases the cat.
The dog is chased by the cat.
In the first sentence the subject (i.e. the dog) performs the action of the verb ‘chases’. This is an ‘active’ construction. In the second sentence, however, the subject (i.e. the dog) experiences the action which is carried out by someone/something else. This is a passive construction.