本段的第一句是段落主题句，指出在城市里有许多旧楼还在发挥着作用。

Many old buildings in cities are still being found useful. In several cities, old buildings that were no longer being used have been converted to a variety of useful structures.

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在英语阅读和写作教学中，正确理解段落主题句，准确把握段落主题句的种类、位置，并掌握其扩展方法，对于提高大学生的英语阅读速度和写作能力大有裨益。

A better understanding of the varieties, positions and ways of development of an English topic sentence in a paragraph is beneficial to learners in improving their reading as well as writing skills.

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最重要的是，你要特别注意段落的主题句。

Most important of all, you should pay special attention to the topic sentence of a passage.

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