都是正确的，使用方法不同。1、catalog常用在说明书和产品目录中。解析：catalog英 [ˈkætəlɒɡ]美 [ˈkætəlɔːɡ] 目录，一览表；系列；种类；产品样本。为…编目录，登记分类；记载，登记（某人、某事的）详情。例句：Here are our catalog and price 这是我们的产品目录和价格表。2、contents常用在书籍中。解析：contents英 [kənˈtents]美 [kənˈtents] 所容纳之物;所含之物；内容；(书的)目录，目次；(书、讲话、节目等的)主题，主要内容。满足；满意；知足；使满意；使满足。例句：There is no initial list of 没有章首目录。扩展资料：contents用法：1、容器的内容物，如瓶子、盒子或房间，是里面的东西。2、书籍、演讲或电视节目的内容，所涉及的主题、所讲述的故事或所表达的思想。3、书籍的目录。
1 Introduction 1 Introduction 2 onions The nutritional content of 2 onion 2 3 The health onion 2 4 juice vegetable juice clarification method 3 1 Enzyme treatment 3 2 deal with ultrafiltration membrane 4 3 to clarify the 5-treated 5 to clarify the preservation methods of onion juice 5 1 Preservation potassium sorbate 5 1 Preservation of citric acid 5 6 Prospect of 6 2 Materials and Methods 6 1 Test materials， equipment and reagents 6 1 Test Materials 6 2 Test apparatus 6 3 Test Kit 7 2 Test Method 7 1 Preparation of onion juice 7 2 onion juice clarification 7 3 to clarify the clarification of onion juice preservation 7 3 Results and Analysis 7 1 onion juice pectinase treatment to determine the optimal dosage of 7 2 onion juice pectinase processing time to determine the optimum water bath 8 3 pectinase treatment of onion juice to determine the optimum water temperature of 9 4 Orthogonal analysis of onion juice pectinase to clarify the role of the optimal conditions for 10 5 to clarify the preservation of onion juice test 11 1 to clarify the degree of cold storage on the impact of 11 2 to clarify the degree of citric acid on the impact of 12 3 Potassium Sorbate onion juice during the period of preservation to clarify the impact of 14 degrees Potassium sorbate and citric acid 4 to clarify the impact of the degree of contrast 15 4 Conclusion 16 5 References 16 6 a vote of thanks 18
