Imperative sentences
Imperative sentences are commands or requests. They *implied* a subject, which is "you," but it is not explicitly stated.
Examples:
* Close the door. (Subject: You)
* Please be quiet. (Subject: You)
* Go to bed. (Subject: You)
Important Note: There are some cases where sentences might seem to lack a subject, but they actually have an implied subject.
* "It's raining." This sentence has "it" as the subject, but it is a dummy subject that stands in for the real subject, which is the weather.
* "There's a cat in the garden." This sentence uses "there" as a dummy subject to introduce the real subject, which is "a cat."
So, while most sentences in English require a subject, imperative sentences are the exception, as they rely on an implied "you."