A simple sentence, is also called an independent clause. It contains a subject and a verb, and it expresses a complete thought.
A. Some students like to study in the mornings.
B. Juan and Arturo play football every afternoon.
C. Alicia goes to the library and studies every day.
The three examples above are all simple sentences. Note that sentence B contains a compound subject, and the sentence C, contains a compound verb. Simple sentences therefore, contain a subject and verb; and express a complete thought. but, they can also contain compound subjects or verbs.
If you want more information. go to my Tumblr Page http://jonaswagieswag.tumblr.com/ :D