上游充通大粤 SHANGHAI JIAO TONG UNIVERSITY Abstract >A short paragraph(200-1000 words)demonstrates the main idea of a report,paper,dissertation or thesis >Usually comes before the main body of the document or manuscript 1B回后Abstract  A short paragraph (200-1000 words) demonstrates the main idea of a report, paper, dissertation or thesis  Usually comes before the main body of the document or manuscript