Is that a sentence? Where is the verb? It certainly appears to be a sentence Fragement to me.

To fix the first sentence and make it a complete sentence, you can add a verb. For example, you can rephrase it as "Is that a sentence? Where is the verb?" In this case, "is" is the verb.

As for the second sentence, "With five gallons of gas" is a prepositional phrase acting as an answer to the question. To make it a complete sentence, you can add a subject and a verb. For instance, you can write, "You can fix this sentence with five gallons of gas." In this case, "you" is the subject and "can fix" is the verb.

When punctuating sentences, it is important to ensure they are grammatically correct and convey a complete thought.

The given sentence, "With five gallons of gas," is a sentence fragment because it lacks a subject and a main verb. To fix it and turn it into a complete sentence, you can add a subject and a main verb. For example, "I can fix this sentence with five gallons of gas."