We can define bot in such a way : a host nation conclude and sign an agreement of concession in which the state confer the concession of investing , financing , operating and maintaining of a large infrastructure to investors . investors pay back the debt of the project and recover the investment by their income from operating 其基本含义是东道国政府与私人投资者签订特许协议，将某一大型基础设施的投资、融资、经营和维护等特许经营权授予私人投资者，投资者在协议规定的特许期内，通过经营所得偿还项目的债务和回收投资，特许期满后无偿的将该基础设施移交给东道国政府。
Part iv is the key of this article , stating a way to perfect the legal - controlling system of domestic venture investmment , on the basis of detailed analysis of existing problems in part iii , through six aspects . they are : ( 1 ) to speed - up the process of legislation to provide firm legal protection for venture investment ; ( 2 ) to adjust fund - raising system to realize the pluralization of investors ; ( 3 ) to attach the limited partnership to the formation of venture investment institutes ; ( 4 ) to strengthen the protection of intellectual property rights in venture investment ; ( 5 ) to perfect preferential tax system , create favored taxiation enviroment ; ( 6 ) to amplify the outgoing systen of venture investment 该部分结合我国国情，着重阐述了放宽对机构投资者的限制和引进国外风险资本，以拓宽风险资本来源的对策;第三个方面对有限合伙制进行了详细的介绍，并将之与公司制进行比照，说明了风险投资机构的组织形式应采用有限合伙制;第四从加强科技成果的专利权保护、明确风险企业中的知识产权归属问题和加强商业秘密的合同保护三个方面阐述了如何加强风险投资中的知识产权保护;第五在简要介绍国内外风险投资税收优惠制度的基础上，从对机构投资者、私人投资者的税收优惠以及税收优惠的对象三个方面，阐述了如何完善税收优惠法律制度，创造宽松的税赋环境;第六为如何健全风险资本的退出机制。
