The second reason is : the tourist industry circles lack cognition or are impercipient in the ideas of sustainable development . relations of man and nature and ecology pretty 因此，旅游学术界急需在环境问题研究上有所突破，需要建立在实践中确实有效的理论和方法体系。
2.
This includes that transaction quantity has been increasing but current efficiency is low , price difference has been reducing but still big , transaction location possesses arrangement but transaction quantity fasten on the ibbm and that transaction variety is increased but no diversification . ( 4 ) the thesis deep - seated probes into the reasons of the mobility problem . in reality , the reasons include illogical interest rate mechanism , lacking the medi - organization , inappropriate structure of bondholders , impercipient market main body , and macro - economic condition etc . all of them limit the mobility of ibbm ( 4 )本文认为产生流动性问题的主要原因在于：利率机制作用不合理，即发行利率机制不合理和一级市场与二级市场利率不对称；交易中介机构欠缺，即做市商制度不完善和经纪人制度缺乏；市场主体结构不合理，即参与者结构不合理和债券持有者结构不合理；市场主体对市场认识不足，即商业银行和其他市场主体对市场认识不足；宏观经济环境等。
