Unit 1 Seeking Business Opportunity Unit 2 Enquiry and Offer Unit 3 Counter-Offer Unit 4 price Unit 5 Quantity Unit 6 Specifications Unit 7 Packing Unit 8 Shipment Unit 9 Payment Unit 10 Insurance Unit 11 Conclusion Unit 12 Inspection Unit 13 Claim Unit 14 Business Promotion Unit 15 Business Online Appendix Ⅰ Appendix Ⅱ Appendix Ⅲ Appendix Ⅳ Reference