The document discusses the four types of sentences: declarative sentences which express facts or opinions, interrogative sentences which ask questions, exclamatory sentences which express strong emotions, and imperative sentences which express orders or commands. It also provides four examples of sentences using these four types: a declarative sentence stating nothing will work unless you do, an imperative sentence ordering to put heart and work into something, a declarative sentence noting nothing comes without hard work, and a declarative sentence observing most people fear responsibility.