The condition of unanimous agreement is too harsh;the principle of absolute invalidity has many disadvantages and the principle of relative invalidity should be more appropriate.

By studying the Cauchy problem of the high-dimensional linear partial differential equation system with variable coefficient on the base of Reference-,We obtain two new practical algebraic criteria for its consistent suitability.

Audit institutions have the audit supervision of construction projects invested by government and government mainly,but the final accounts of completion is not necessarily legally binding on the contractor,however,engineering settlement should be on the basis of the agreement of contract.