Read the following paragraph and underline the topic sentence. Paraphrasing，as well as quotation，is an essential skill in writing research papers. Paraphrasing is used for different purposes. Some paraphrases will be designated to support already existing evidence. Others will reinforce argumentation against evidence. Still others will help to develop existing arguments and provide back-up for any conclusion drawn in the course of writing. Depending on the function，paraphrases will be introduced in accordance with their unique context.
Paraphrasing is used for different purposes.
