* "Understood subjects" are often implied, not stated. This means we have to infer the subject based on context.
* Context matters. The context of the sentence and the overall conversation will heavily influence what the understood subject is.
* First person isn't the only possibility. Understood subjects could be second person (you) or third person (he, she, it, they).
Here are some examples to illustrate:
* "Go to the store." This is a command, and the understood subject is *you*.
* "I'm going to the store." This clearly states the subject as *I*.
* "Leaving now." This is a very short sentence. The understood subject could be *I* (meaning *I am leaving now*) or *he/she* (meaning *He/she is leaving now*).
To determine the understood subject, consider:
* The form of the verb. Imperatives (commands) usually imply *you* as the subject.
* The context of the conversation. Who is speaking and who is being addressed?
* Previous sentences. If the sentence is part of a larger conversation, the previous sentences might reveal the subject.
In summary: While understood subjects can sometimes be first person, they can also be second or third person. There is no hard-and-fast rule, and you must rely on the context to determine the subject.