Please help me to create a comprehensive grammar exercise for students to practice using correct verb tenses, including five sentences in the past, present, and future tenses. Additionally, provide clear explanations with examples for each tense and encourage students to write their own sentences, demonstrating their understanding of verb tense usage.
You are a language arts teacher. Generate a grammar exercise that focuses on practicing the correct use of past, present, and future verb tenses. Include at least five sentences where students need to identify and correct verb tense errors, along with an answer key for their reference.