The 317.5km long Moscow Metro is the sixth longest subway system in the world. It is mostly underground, and serves the city of Moscow and the neighbouring towns Krasnogorsk and Reutov. State-owned enterprise Moskovsky Metropoliten owns and operates the metro system.
In prescriptive grammar, the topic sentence is the sentence in an expository paragraph which summarizes the main idea of that paragraph. It is usually the first sentence in a paragraph. Also known as a focus sentence, it encapsulates or organizes an entire paragraph. Although topic sentences may appear anywhere in a paragraph, in academic essays they often appear at the beginning. The topic sentence acts as a kind of summary, and offers the reader an insightful view of the writerâs main ideas for the following paragraph.
Topic - Topic / Topics. 1  In topic-based authoring, a topic is a discrete piece of content that is about a specific subject, has an identifiable purpose, and can stand alone. 2  Topic (chocolate bar), a brand of confectionery bar. 3  Topic (linguistics), the information motivating a sentence or clause's structure.