Final answer:
A preview of main points reassures the audience by providing a clear roadmap of what will be discussed, helping them understand the structure and organization of the content and generating interest and anticipation.
Step-by-step explanation:
A preview of main points reassures the audience by providing a clear roadmap of what will be discussed in a presentation or essay. It helps the audience to understand the structure and organization of the content, making it easier for them to follow along and comprehend the information being presented. Additionally, a preview of main points can generate interest and anticipation, as it gives the audience a glimpse of what they can expect to learn or discover.