In English, sentences have two basic parts: a subject and a verb. When these two items are linked together in a sentence, a clause is produced. In fact, any phrase that contains both a subject and a verb is a clause. Some clauses can contain two verbs. These constructions are called compound verbs, meaning that two verbs appear in a single sentence, even when there is only one subject.
A compound verb structure, by definition, contains two or more verbs that describe the same subject. For example: "Carla drove to the vet's office and retrieved her cat." This sentence could easily be split into two different sentences. For example:"Carla drove to the vet's office. Once there, she retrieved her cat." However, the sentence pair takes more space, more words and more time to read. In turn, the first sentence is more economical. This sort of organization makes the writing more efficient.
Two verbs may also appear in a single sentence if one of those verbs is a helping or auxiliary verb. In these cases, the two verbs within the sentence are not on equal standing. Helping verbs such as "am," "is," "were" and "can" are largely employed to alter the tense of a verb phrase. For example: "Janice's paintings were sold at auction." Here, the compound verb phrase comes from the linking of the auxiliary verb "were" and the past participle "sold." Other examples include: "I am fond of spaghetti," "We will see a movie tonight" and "They were riding bicycles."