Final answer:
A topic sentence expresses the main idea and focus of a paragraph, providing a clear direction and preview of the paragraph.
Step-by-step explanation:
A topic sentence is a sentence that expresses the main idea or focus of a paragraph. It helps to introduce and organize the information that will follow in the paragraph and provides a clear direction for the reader. In other words, it serves as a preview or summary of what the paragraph will be about.
For example, if the topic of a paragraph is 'Benefits of exercise,' a topic sentence could be: 'Regular physical activity offers numerous advantages to both the mind and body.'
By including the main point of the paragraph in a topic sentence, readers can quickly understand the purpose of the paragraph and the specific details that will be discussed in it.
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