Which of the following options is a complete sentence?

Question

Quizplus · Accepted Answer

Every sentence must contain a subject and predicate.
The subject of a sentence is the person, place, thing, or idea that is doing or being something. You can find the subject of a sentence if you can find the verb. Ask the question, "Who or what is performing the action in the sentence?" and the answer to that question is the subject.
The predicate is the part of a sentence or clause containing a verb and stating something about the subject.
"Be careful not to make grammar mistakes." is an imperative sentence, which simply means that it is a command. The subject of imperative sentences is "you." It is not stated, but it is implied because the speaker is telling "you" to do something, such as to be careful not to make mistakes.
Therefore, "Be careful not to make mistakes." is a complete sentence because the subject is "You" and the predicate is "Be careful not to make grammar mistakes."
Being careful not to make grammar mistakes. is not a complete sentence. There is no subject in this sentence ("being careful" and "be careful" are not the same, so this isn't considered a command because it uses the wrong form of the verb).
As I am careful not to make grammar mistakes. is not a complete sentence since it begins with "as," which implies something else is happening, but is not included in the sentence. There is not a complete predicate here.
Since I am careful not to make grammar mistakes. is not a complete sentence as it begins with "since," which implies something else is happening, but is not included in the sentence. There is not a complete predicate here.

Which of the Following Options Is a Complete Sentence