It really depends on what the complete sentence.
explain why 7*8 is not a number sentence
"Explain your answer."
He asked the teacher to explain the question.We cannot explain what caused the strange lights.
I say yes, but I can't explain why. Just look at it: Listen. It is a complete thought. There is an implied audience, and definitely a fully expressed idea, but I cannot call this a technical answer... just my thoughts. Yes, it is a complete sentence. It is the predicate (verb); the subject is understood. It is a command/statement. It is the sams as "Stop." or "Wait."
Dalila had to explain to the class about her project .
A complete thought does have a verb; but having a verb does not make a group of words a complete thought. A complete thought must have at least one verb, but a complete thought can also have several verbs.An incomplete though that does have a verb is called a clause.A group of words becomes a sentence when it is a complete thought. Some examples:The cookies that Mary made were passed out to the class. (The dependent clause 'that Mary made' has a subject and a verb, but it is an incomplete thought.)I watched TV while Mary washed the dishes, packed the lunches, and made some coffee. (There are four verbs in the sentence, but the sentence is a single complete thought.)
My teacher asked me to explain why I was late for class.Photosynthesis is difficult to explain.
To explain something within the sentence without finishing the sentence before explaining.
the product of a multiplication sentence is the answer to a multiplication sentence.
They turned to superstition as well as religion to explain away the causes.
rule that could explain what makes a sentence grammatically correct or not before the noun."