I really don't like pizza. I don't really like pizza. I used to smoke a lot. But I don't now. This tells us that 'used to' is understood to be in the past.
Translation is also an important tool in a monolingual situation.
Using timelines followed by questions to check understanding of verb tenses. I arrived Use the same line of questioning for each tense you teach. Be as thorough as possible without losing the students' interest. Checking can be oral, but using the blackboard provides a visual record of meaning. A high level of understanding and learning depends to a large extent on the material being presented at the right level, and being well presented with activities designed to capture and keep a student's attention.