According to Chinese Guarantee Law, a valid guarantee must have some valid requirements; otherwise it is an invalid guarantee, in which situation, the guarantor, creditor and debtor will undertake the relevant civil liabilities in correspondence with their faults.

The influent quality of the two existing wastewater treatment plants in Xi'an was investigated,and the methodology for determination of the influent quality as the basis for design of WWTP according to the frequency of pollutants concentration in wastewater(assurance rate of 85%)was put forward.

The article gets an optimization method of linear programming of elasticity constraints by using the content extent function and assurance rate.

The research indicated that,85% of assurance rate could be used to insure the effluent quality meet the standard.

With the calculation of two practical examples,the results show that the guarantee rate of concrete core strength central value from cast-in-situ concrete pile based on Quality Inspection and Evaluation Standards for Highway Engineering(JTJ071-98) i.

The features of the special vehicle carrier s type are introduced in the paper and the statistics for the main dimensions are made by the method of guarantee rate according to the data of LLOYD S REGISTER OF SHIPPING and the Catalog of Nippon Ships.

According to statistics analysis of 30 years air temperature and field temperature in the hottest and the coldest month,it was suggested that high pavement design temperature should be determined by the average high field temperature with 98% assurance rate in seven consecutive days,the low pavement design temperature should be determined by the lowest field temperature of a .